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WORKS MANAGEMENT LIBRARY 



PREVENTING LOSSES 



IN 



FACTORY POWER PLANTS 



DAVID MOFFAT MYERS 




NEW YORK 

THE ENGINEERING MAGAZINE CO. 

1915 



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Copyright, 1915 
By THE ENGINEERING MAGAZINE CO. 



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M4R 3 1915 



©CI.A393820 



E. H. M 



- INTRODUCTION 

There are usually four stages in the industrial 
evolution of a productive civilization such as that of 
the United States. The first is the frontier stage. 
All the men and most of the women work with their 
own hands. The important industries . are those 
which have to do with the needs for food and clothes 
and housing. There is little surplus wealth and little 
spending. The hunter and the trapper is gradually 
being replaced by the farmer and the cattleman. The 
factories are small, and supply a local market: the 
employed class is not numerous at any one place. 
Each village or town is largely self-dependent. There 
are many mechanics in business for themselves. 

The second era appears with the miner, the pro- 
ductive manufacturer and the development of trans- 
portation. The industries produce more than the 
local market can use, and more of a different kind, 
by reason of the aggregated labor and its economies. 
Supported as to food and clothes and housing, and 
with the highway and the railed way seeking to con- 
vey goods and raw material, an excess of wealth be- 
yond that required to meet primary needs seeks in- 
vestment and return. Greater factories arise, co- 
ordination of competitive interests takes place, and 
the era of "big business," of extending railways, of 
good highways, of luxury, leisure, of culture and of 
art begins. 

The third stage may be called the era of Eefine- 
ment in Production. These are the days of better 
business management, of economies of administra- 



11 INTRODUCTION 

tion, of lowered costs of production and of power, 
of hydro-electric developments, of co-operation in 
production, of effort to reduce the cost of living. 

The fourth stage is the era of Uplift. The cap- 
tains of industry see not alone that it is their duty 
to make the producer wealthy, and the factory effi- 
cient and economical, but also that the human ele- 
ment must be healthy and life worth living. These 
are the times of securing safety and sanitation, of a 
recognition of the truth that the life is more than 
food and the body than raiment; that the employer 
is his brother's keeper. 

Now the book of which these few lines are an in- 
troduction belongs to the third epoch and the begin- 
nings of the fourth. It concerns itself with the re- 
duction of operating costs in the power-plant, and 
aims to apply the methods of sound science to the 
problems of the production of power. The Author 
has specialized in the field of boiler-plant economy 
and fuel, and writes with the authority of experience 
in this and related departments of research. The 
treatment of power-plant losses is the outcome of 
study of the usual ignorances of executives and su- 
perintendents. The application of the principles ad- 
vocated has actually effected savings of many thou- 
sands of dollars annually. The treatment is to con- 
vince the business end of the productive process, as 
represented by the owner and manager. It should 
be convincing, as the combination of theory and 
practice has been experimentally worked out. The 
power-plant has not been as attractive a field as some 
others to the so-called efficiency engineer; and the 
Author has had the privilege of recognizing the 
human factor in its basal relations to success. This 
puts the book in its pioneer place of literature as 
respects the fourth epoch of industrial evolution, 
and the ninth chapter should receive careful study. 
Data and conclusions on the combustion process, 
fuels, testing of steam generators, and the reporting 



INTRODUCTION 111 

on any investigations made are features of the later 
chapters. 

The relations of the Author and the writer of this 
introduction were at first the pleasant ones of the 
professor of engineering and the enthusiastic student. 
These have continued and developed into those of the 
affection of the older man for the younger and in- 
terest in his successful achievements. The start of 
the younger in the lines of thinking that the me- 
chanical engineer must be also a business man is the 
older man's contribution. The development of that 
idea is the younger man's achievement as this pre- 
sents it. 

Frederick Eemsen Hutton", 
Past President, American Society of Mechanical En- 
gineers, 



PREFACE 

This book has been written expressly for the use 
of the owners and managers of our manufacturing 
industries. 

My object is to set before them, in as brief and 
direct a manner as possible, the basic information 
which they require for the intelligent handling of 
their power-plant problems. 

With this idea in view, I have in my introductory 
chapters laid stress upon those fundamental princi- 
ples and natural laws which are essential to a proper 
understanding of the numerous questions of specific 
nature which are later more fully developed. 

As a feature of consequent importance I have 
given the actual application of the theories to the defi- 
nite problems in hand, in order to show their direct 
relation to the striking economies which result from 
their practice. 

All of these matters are broadly covered in the 
first nine chapters, and are so composed as to present 
a birdVeye view of the entire subject for easy review 
by those executives whose limited time would pre- 
clude a more exhaustive study. For such, this first 
section alone has been specifically prepared. 

The remainder of the book is given over to the fur- 
ther and more detailed study of the questions natur- 
ally arising from a perusal of the first part, and log- 
ically belongs more especially in the field of the me- 
chanical superintendent and the factory engineer. 



VI PREFACE 

The book, as a whole, and, in so far as its limited 
size allows, represents present practice in the work 
of improving factory power-plant efficiency, and indi- 
cates the trend of advance which the future portends, 
both on the side of equipment and of operation. 

Were I permitted the publication of but a single 
chapter of this book my immediate choice would be 
in favor of the ninth on the "Human Factor". For, 
by confining my expression to this single chapter, the 
object of the book would suffer in a less degree than 
would be the case if I had to be contented with any 
six of the others. 

For the subject-matter of this work my principal 
acknowledgments are respectfully offered to my 
clients, the manufacturers, in whose establishments 
and with whose co-operation I have been enabled to 
study and apply the principles of efficiency for the 
building up of economy and the reduction of prevent- 
able losses in factory power plants. 

David Moffat Myers 

New York, October, 1914. 



CONTENTS 

Chapter I. The Determination of Existing 
Losses 1 

Foundation principles — definition of effi- 
ciency — relation of waste to efficiency — the 
laws of the conservation of energy — effi- 
ciency standards fixed by natural law — per- 
petual motion — determination of existing 



Chapter II. Attainable Efficiency and 

Ordinary Wastes 20 

Over-all and individual efficiencies in a 
factory power plant — thermal efficiency ver- 
sus commercial efficiency with example — 
formula for commercial efficiency — synopsis 
and diagrammatic illustration of the ther- 
mal operation of a typical factory power 
plant: — steam balance showing distribution 
■ — electrical and mechanical transmission 
systems compared — the conservation of 
energy the fundamental basis of all power- 
plant work — individual and over-all effi- 
ciencies — waste in the boiler plant, in the 
engine plant, and in connection with exhaust 
steam — primary importance of boiler-plant 
efficiency as affecting the over-all economy 
of the whole plant — diagrammatic illustra- 
tion Figure 8 — steam-engine efficiencies — » 



Vlll CONTENTS 

use of exhaust steam a critical factor — plan" 
of a factory power-plant investigation. 

Chapter III. The Boiler Plant 48 

Investigating preventable losses in the 
boiler plant — preliminary precautions — effi- 
ciency determinable only by proper test — 
unreliable reports and data — definition of 
boiler efficiency — factor of evaporation — the 
heat balance — its use demonstrated by ac- 
tual case from a report — discussion of each 
item of heat loss. 

Chapter IV. The Boiler Plant (Con- 
tinued) . 79 

Causes of inefficiency from design — fac- 
tory boiler requirements — specification of 
heating surface and number of boilers for 
given conditions — illustration from report 
— fire-tube versus water-tube boilers — cost 
of evaporation — feed-water conditions as 
related to economy — purification of feed 
water — temperature of feed water — coal 
and ash handling — boiler-room records. 

Chapter V. Steam Piping and the Engine 

Plant 103 

Piping losses and their reduction — super- 
heated steam — the engine — present attain- 
able efficiencies — possible efficiencies — effect 
of condensing versus non-condensing — 
utilization of the exhaust steam and its 
importance — necessity of considering the 
heating requirements with the engine plant 
— maximum engine efficiency when exhaust 
steam is used — a steam engine as a reduc- 
ing valve — effect and correction of back- 



CONTENTS IX 

pressure losses — superheated-steam econo- 
mies in engines. 

Chapter VI. Preventable Losses in the 

Engine Plant 126 

The steam engine — losses from friction, 
cylinder condensation, leakage, incomplete 
expansion, wire drawing, and clearance vol- 
ume—methods of reducing these losses — 
exhaust-steam turbines — the internal-com- 
bustion engine — its special fields of service 
— cost of power with efficiency of internal- 
combustion engines — the Diesel engine — oil 
engine versus steam engine — gas-producer 
plants — heat balance of a gas engine — heat 
losses of the internal-combustion engine 
and their reduction — the water turbine — 
purchased power versus making power in 
the factory plant — engine-room efficiency 
record blank. 



Chapter VII. The Heating System 154 

Comparison of heat in exhaust steam with 
that in steam at high pressure; a practical 
demonstration — efficiency of heating — defi- 
nition and example — value of returning 
hot drips as compared to saving by utilizing 
exhaust steam — case where power is by- 
product of the heating — efficiency of radiat- 
ing surface or "Rate Efficiency" — substi- 
tuting low-pressure exhaust for high-pres- 
sure steam in a heating system — factors re- 
quiring consideration — Corliss engine as a 
reducing valve — a combined power and 
heating plant develops the highest attain- 
able efficiency — a horse-power hour for % 
lb. of coal. 



CONTENTS 



180 



Temperature limitations of exhaust steam 
—difference between temperature and 
heat— high-pressure heating liable to 
greater waste than low-pressure heating- 
steam traps-functions of steam trapf- 
loss from badly laid out drip lines-deter- 
mmation of heating requirements. 

° H ™4 IIL . . The He ™ s — (*- 

m "Indirect" heating calculations— balanc- 
ing exhaust steam to heating demand of 
vital economic importance— working prin- 
ciples of factory heating design-the vac- 
uum return-line system and types of 
vacuum valves»-heating plan and illus- 
trations—the vacuum air-line system- 
direct versus indirect heating— vacuo hot- 
water system. 



Chapter IX. The Human Factor 199 

One-fourth of the coal bill controlled bv 
the fireman-the fallacy of the "good man" 
theory of operation— means for checking 
efficiency are essential— faults of the man- 
agement leading directly to wastefulness- 
old-school methods" and guesswork— the 
nreman; his working conditions— relation 
of humanity to economy-profit sharing in 
the boiler room— science and system essen- 
tial to results— educating the fireman— the 
responsibility of the president and direc- 
tors—dangers in the power plant— their 
correct] on-^saf ety recommendations— safe 
piping plan. 



CONTENTS XI 

Chapter X. Efficiency Systems for Boiler 

Plants 231 

General requirements of an efficiency sys- 
tem in boiler plants — different systems for 
different conditions of management — actual 
case of standardization — three boiler plants 
with determination of individual standards 
— computation of evaporation standards — 
bonus system based on actual evaporation 
— boiler-efficiency system for use where su- 
perintendent or chief engineer is technically 
trained — determination of bonus — efficiency 
standards — efficiency chart and its use — 
— commercial efficiency system in use in 
plant where coals of varying prices and 
values are obtained — results from its use — 
coal-mixture table — evaporation table show- 
ing cost per 1,000 lb. of steam — cost-of- 
evaporation curves for use in factory 
plants. 

Chapter XL Boiler Tests 246 

Bituminous Coal. — Tests made in fac- 
tory plants, showing good and bad results 
under various conditions with various 
grades of bituminous fuels, with discussion 
of causes for the results obtained in each 
case — internally fired boilers — tests giving 
both high and low efficiency — influence of 
human factor, with discussion of require- 
ments for internal firing of soft coal — 
horizontal tubular boilers hand-fired — good 
results and bad results, with conditions 
surrounding the individual performances — 
down-draft system of combustion — tests 
showing high results, with description of 
furnaces and operation. 

Anthracite Coal. — Two complete tests 



Xll CONTENTS 

on water-tube boilers with buckwheat coal, 
showing good results and bad results respec- 
tively, with analysis of tests showing reason 
for efficiencies obtained — buckwheat coal 
and forced draft with horizontal tubular 
boiler — complete tests showing good results, 
with surrounding conditions — discussion on 
the combustion of fine sizes of anthracite — 
natural draft versus mechanical draft. 

Chapter XII. Combustion 311 

Common errors prevalent in combustion 
engineering — chimney losses, wet and dry 
— heat-producing constituents of coal — 
complete combustion and perfect or chem- 
ical combustion defined — nomenclature 
used in discussion — Deduction, of dry chim- 
ney loss in the complete combustion of one 
pound of pure carbon to C0 2 with varying 
amounts of air — composition of air as de- 
termined by Sir William Eamsey — Avaga- 
dro law applied to flue gases — oxygen and 
air required for combustion — volumetric 
analysis related to weight of products of 
combustion — specific heats involved — calcu- 
lation of heat loss — pure-carbon curve re- 
sulting from above deduction — Deduction of 
dry chimney loss from the combustion of 
actual bituminous coal — definition of com- 
bustible — effect of the oxygen constituent 
on B.t.u. — actual oxygen bomb-calorimeter 
test for B.t.u. — air requirement reduced by 
oxygen in the coal — method of computing 
the net air required — definition of H a — 
original volume of oxygen in air not meas- 
urable in Orsat with a fuel containing H a 
— nitrogen in the Orsat — sum of the gases 
as affected by H a , and example — pure hy- 



drogen-fuel flue-gas analysis — analysis of 
the coal used in the determination — H a 
determination — formula deduced for volu- 
metric analysis of flue gas of coal and maxi- 
mum C0 2 possibles with a given or found 
H a — effect of excess air included in for- 
mula, air required for the coal determined 
and its relation to G0 2 in the Orsat • 
analysis — weight of combustion products 
formula and its deduction — specific heats 
involved — final formula and computation of 
dry chimney loss — actual coal curve show- 
ing dry chimney loss constructed by above 
method — Determination of H a in a fuel 
from flue-gas analysis — deduction of for- 
mula which includes presence of CO — 
example — Air required by a fuel from flue- 
gas analysis — example — Approximate heat 
value of a fuel determined from flue-gas 
analysis — example — natural gas — errors in- 
volved — coal example — this method of 
scientific interest only — Loss due to CO in 
flue gases — formula deduced — example — 
curve showing loss due to CO — Wet chim- 
ney losses — loss due to moisture in the fuel 
— formula and example — loss due to the 
burning of hydrogen — formula and example 
— loss due to moisture in the air — Heat 
balance of a boiler and furnace test — 
complete list of items and their accounting. 

Chapter XIII. Surface Combustion - 342 

Cause of inefficiency with ordinary com- 
bustion — chimney loss a minimum with 
surface combustion — efficiencies obtained — 
— high evaporative capacities compared to 
other boilers with requirements for, and 
operation of, surface combustion — back 



XIV CONTENTS 

firing — maximum temperatures obtainable 
— formula for furnace temperature — pre- 
diction of the future for nameless combus- 
tion as applied to boilers — oil burning — 
gas burning — coal burning — illustrations. 

Chapter XIV. Natural Gas as a Boiler 
. Fuel 357 

Composition — heating power by calcu- 
lation, by calorimeter test — efficiency, evap- 
oration, etc., from boiler tests — effect of 
pressure and temperature on heating 
value — gas equivalent of coal — computation 
— price of gas to compete with coal; ex- 
ample — qualifications of a good gas burner 
— draft required for gas burning — gas burn- 
ers illustrated — flue-gas analysis — effect of 
hydrogen in gas — five boiler tests on natu- 
ral gas. 

Chapter XV. Natural Gas (Continued). 

Gas Engine versus Steam Engine 385 

Commercial efficiency of gas-fired boiler 
with steam engine compared to gas engine 
with different types of plants — influence 
of price of gas on the problem — method of 
solving problems of this kind — tests on 
natural-gas engines. 

Chapter XVI. The Economic Combustion 

of Waste Fuels 394 

Section I. Introduction — principles in- 
volved — requirements for economic combus- 
tion and difficulties encountered. 

Section II. Sawdust and wood waste — 
five different methods of denoting calorific 
power of a waste fuel — importance of spe- 
cific designation of method used. 

Unreliability of Dulong's formula for 



CONTENTS XV 

computing heat values of waste fuels and 
the reasons — furnace designs for special 
conditions described and illustrated. 

Tan bark as a boiler fuel — furnace de- 
signs and results obtained — furnaces for 
burning a mixture of tan and coal — chest- 
nut-extract chips — licorice chips. 

Section III. Bagasse or waste sugar 
cane — furnaces for best efficiency — operat- 
ing performances — heat value, etc. — culm 
furnaces and results — heating values, etc. 
— briquettes — powdered-coal burning — coke 
braize — city refuse and its treatment for 
successful combustion — destructors and 
furnaces — conclusion. 

Chapter XVII. Boiler-feed Pumps — Steam- 
Consumption Tests 469 

Importance of determining exhaust steam' 
of pumps — tests made under factory condi- 
tions — steam consumption given in terms 
of boiler output — method of testing — analy- 
sis of the steam-pump efficiency — compari- 
son with efficiency of steam engine. 

Chapter XVIII. Modern Types of Prime 
Movers 478 

Eecent developments — prime movers 
adapted to factory practice — Steam- — the 
locomobile — the unaflow engine — Oil — the 
Diesel engine — the De La Vergne engine. 

Chapter XIX. Eeports 508 

Complete investigation of a factory 
power plant — actual reports covering in- 
vestigation and tests in a factory power 
plant to determine the question of making 
versus buying power, with recommenda- 
tions; and tests made on the revised plant 



CONTENTS 

after the recommendations made in the first 
report had been carried out, with report on 
savings effected as a result of the initial 
investigation — reasons calling for the in- 
vestigation — general situation described — 
cost of purchased power — cost of power with 
plant as found — entire problem resolved 
into three specific questions — method em- 
ployed for their determination — charges to 
fuel, labor, maintenance, repairs and in- 
terest determined — analysis of existing 
book-keeping with regard to power costs 
— form of condensed report — all tests and 
data to substantiate conclusions included in 
full report — saving in first cost of $33,000 
as one result of the investigation — net sav- 
ing in operating costs 71 per cent on invest- 
ment recommended. 

* The Initial Investigation (First Eeport). 
Eecommendations — steam for mill require- 
ments tested, steam used at night — effi- 
ciency test of boiler plant — costs of evap- 
oration — flue-gas analysis — boiler-plant ca- 
pacity as bearing on problems in hand — 
boiler-plant efficiency — power-plant operat- 
ing cost sheet — cost of power with present 
equipment — main-engine efficiency and ca- 
pacity — all day test — determining electric 
power required, by test and by checking 
with cost accounts — cost of making versus 
buying under all the determined conditions. 
Second Investigation and Eeport after 
Eecommendations Were Executed. Object 
of the investigation — condensed results — 
plan of tests — new engine — effect of speed- 
ing up main engine — test on main engine 
and generator — test on new engine and gen- 
erator — cost data from books — notes on 
charges against engine. 



PREVENTABLE LOSSES 
IN FACTORY POWER-PLANTS 

Chapter I 

THE DETEEMINATION OF EXISTING 

LOSSES 

"TpVERYONE who is any way connected 
-"^ with the great problems of the times is 
vitally concerned with the extensive subject 
of preventable losses. Broadly as well as 
definitely considered, all the questions of to- 
day depend for their ultimate solution upon 
a thorough and exhaustive analysis of pre- 
ventable losses. The science of medicine, 
the practice of surgery, are aimed at preven- 
tion beforehand rather than an attempted 
cure after the physical breakdown has oc- 
curred. This results in the saving of life 
and health, the improvement of human effort, 
1 



2 PREVENTING POWER-PLANT LOSSES 

and the countless benefits that are produced 
in so many directions. When preventable 
losses have been eliminated, increased effi- 
ciency is the direct result. 

This simile may be extended indefinitely. 
Take the great social problems. The work- 
ers and reformers are striving diligently to 
understand those elements in our social sys- 
tem which are at the foundation of the ex- 
isting losses, mental, moral and physical, 
toward the prevention of which they have 
devoted their efforts. The aim is first by 
study definitely to locate, and then finally 
to eliminate those elements which destroy 
human efficiency. No matter what the prob- 
lem, the method of attack both logically and 
actually is the same. Determine the prevent- 
able losses, gain knowledge of their respec- 
tive causes, and then intelligently and effec- 
tually eliminate them. 

Turning now to a consideration of prob- 
lems of engineering, we begin to deal with 
elements that are more definite. We have 
a vast amount of reliable data from which 
formulae have been deduced. These formulae 
have been applied to actual work and the 
work has proved their value. 

The new and growing science of efficiency 
engineering as applied to production, al- 
though as yet in the days of its infancy, has 



DETERMINING EXISTING LOSSES 3 

achieved some very remarkable results. The 
various leaders and workers in this field, 
although differing considerably in their 
methods and in their theories, are all united 
in the one effort — that of reducing prevent- 
able losses to a minimum. 

But in this field the engineer is compelled 
to make for his work in hand a definite or 
maximum standard of efficiency, and toward 
this standard he directs his efforts. It fol- 
lows that the careful establishment of this 
standard is perhaps the most important fea- 
ture of his work. This standard or degree 
of efficiency, when set by the competent ex- 
pert, is always a practical one, and can be 
attained by the best known practice of the 
profession with savings which at times seem 
wonderful when compared with old-time 
practice. 

For all work of high accomplishment an 
ideal must be had toward which to work. 
This ideal must be kept constantly in mind 
and all results judged in comparison with 
this work, which should represent 100 per 
cent efficiency. The physician, the social 
worker, the efficiency engineer, must each 
possess a vision of their respective ideals, 
their marks of 100 per cent efficiency, the 
physically perfect body and mind, the perfect 
unit of human society, the perfect process 



4 PREVENTING POWER-PLANT LOSSES 

for production without loss. All imaginary, 
all visionary, but absolutely essential and 
with tremendous power for inspiration and 
attainment. 

And here, too, arises great difficulty. For 
in most fields of operation there is wide di- 
vergence of opinion as to what constitutes 
the ideal, the perfect result. In medicine 
great discoveries are made. An additional 
disease is brought under control. But the 
question is how much more can medicine ac- 
complish even if perfection of knowledge is 
reached? No answer is possible. 

In society great reforms have been ef- 
fected. Great good has resulted. But what 
is the ultimate good that will result, the 100 
per cent moral efficiency? What is the stand- 
ard, the perfect human ideal whereby all lives 
may be accurately and truly measured? It 
is the very diversity of ideals, the lack of 
knowledge of the one perfect universal truth, 
that prevents more rapid progress toward 
that perfect unit and body of human society 
so desired and so necessary. 

In production or efficiency engineering, 
after great savings have been made, more 
savings still are discovered to be possible. 
It is impossible to know at what point the 
limit of economy will be reached. It cannot 
be known what constitutes 100 per cent effi- 



DETERMINING EXISTING LOSSES 5 

ciency or how much preventable loss still 
remains after all brain power and training 
have been exhausted. The same truth applies 
to the science of machine design. A device 
is invented which increases production and 
reduces the unit cost perhaps 25 per cent. 
Can a still better machine be devised which 
will reduce to a still further extent losses 
that in the light of present knowledge and ex- 
perience evade all attempts at discovery! 
The answer is a question. There is no 100 
per cent efficiency with which to judge, and 
future improvement is entirely problematic 
both as to its possibility and as to its extent. 

Among all the problems of our time there 
is a very important one which possesses the 
tremendous advantage of a definite deter- 
minable ideal. The 100 per cent efficiency 
of the perfect power plant is known and 
understood. The processes involving the 
production of " power", in glowing contrast 
to almost all other processes, are subject to 
absolute and ultimate analysis. This state- 
ment is true for all sources of power and for 
all methods of converting latent energy into 
active work. 

As an instance consider water power. If 
we have a stream supplying 1,000 pounds of 
water per minute with an available head of 
33 feet, a perfect turbine or water wheel 



6 PREVENTING POWER-PLANT LOSSES 

would convert all the potential energy of 
the water into useful work ; that is, we should 
receive 33,000 foot pounds of energy per 
minute because that is the full amount of 
energy in the water. It is therefore impos- 
sible to obtain more than this amount. Ac- 
tually we shall obtain much less, and with 
certain forms of wheel perhaps only one-half 
this amount. In this case the efficiency of 
our process is exactly 50 per cent and our 
losses are 50 per cent. We know that our 
limit of possible improvement in our machine 
is 100 per cent, or a maximum of 33,000 foot 
pounds per minute or one horse power. 
Hence we have fixed for us by natural laws 
a definite standard, a 100 per cent efficiency 
mark which represents absolute perfection. 
If a turbine could be designed which would 
develop energy at the rate of one horse power 
from 1,000 pounds of water falling 33 feet 
per minute we should know definitely that 
we had evolved a perfect process and that 
no more improvement would be possible. 
There would be no further losses to over- 
come. Owing, however, to friction and other 
fixed causes we do not expect to obtain 100 
per cent efficiency. If this could be done our 
turbine would be able to pump the water it 
had used up over the dam again, thus re- 
establishing its source of power and we 



DETERMINING EXISTING LOSSES 7 

should then have the much dreamed of "per- 
petual motion ". 

I. have more than once been called upon 
by capitalists to investigate perpetual-motion 
machines, usually called by other names for 
the purpose probably of misleading the inno- 
cent investor, and I will offer to such an 
added word of advice. If all friction and 
other natural inherent losses could actually 
be overcome and a perpetual-motion machine 
could be designed and made to operate, it 
would still be absolutely worthless for the 
purpose of running machinery or doing any 
kind of work whatever. This, for the simple 
and comprehensive reason that it would have 
to expend every foot pound of energy devel- 
oped in order to re-establish its source of 
power, and there would therefore be no sur- 
plus energy available for purposes of outside 
work. If it could be conceived that a per- 
petual-motion machine could be made to 
work, it would come to an instantaneous 
standstill as soon as a dynamo or any other 
load was imposed upon it. 

This simple example illustrates accurately 
and with forcible truth the fundamental prin- 
ciple underlying and making possible all work 
of genuine investigation and improvement 
in the field of power-plant operation and de- 
sign. This underlying truth is known as the 



8 PREVENTING POWER-PLANT LOSSES 

principle of "the conservation of energy.' ' 
Otherwise stated, energy can neither be de- 
stroyed nor increased. It is true that energy 
can be transformed from one manifestation 
to another, and this is a most common occur- 
rence in Nature. Thus the heat of the sun 
evaporates water from the sea. This water 
is precipitated in rain on the mountains 
where vast reservoirs of latent energy are 
available by application of the water wheel, 
and mechanical energy is thus the direct 
result of the evaporative power of the heat 
rays from the sun. 

In power work the mechanical energy of 
the water wheel is converted into the elec- 
trical form of energy through the medium 
of the dynamo. The latent heat of coal 
through the agencies of the furnace, the 
boiler, and the engine, is transformed into 
mechanical energy. Through the generator 
connected to the engine it becomes electrical 
energy, and once again through the motors 
it is converted back into the mechanical form 
of work on line shaft and moving machinery. 
Thus we have many instances w r e may call 
to mind which illustrate the transformation 
of one form of energy to energy of another 
form. 

In the foregoing example of transforma- 
tion it will be realized that the final amount 



DETERMINING EXISTING LOSSES 9 

of energy developed in the machinery is less 
than the energy supplied to the motor which 
drives it. That supplied to the motor by 
the dynamo is less than that it in turn re- 
ceived from the engine, while the engine 
transforms into useful work only a very 
small fraction of the heat energy it derived 
from the boiler, and finally the boiler gives 
to the engine in the form of steam only a 
part of the heat that was applied to the boiler 
in the form of fuel. Thus we have a series 
of energy losses, at least one for each trans- 
formation, all the way from the coal in the 
boiler room down to the machinery in the 
factory which it is intended to operate. 

This being the case, the reader may object 
that the conservation principle does not hold 
true, for we have started with 100 per cent 
of heat energy in the coal and when we meas- 
ure the amount of actual output at the dyna- 
mo or the motor we find only a small fraction 
of the original input, and the balance is sim- 
ply lost or dissipated in some unaccountable 
way. The whole matter appears to be a mys- 
tery or else the principle of conservation is 
all wrong and unreliable. 

As a matter of fact, however, there is no 
more beautiful method of proving the con- 
servation theory than to start with 100 heat 
units of energy in the coal pile and to follow 



10 PREVENTING POWER-PLANT LOSSES 

each successive step in its various processes 
of transformation and transmission until we 
find at the end of this journey the exact 
amount of useful work our calculations will 
have called for. 

The greatest feature of power investiga- 
tion lies in our ability to account accurately 
for all units of energy, from their original 
liberation down to the final amount of useful 
work that has been produced. This final 
amount of energy or the useful output of the 
plant when compared to the original input 
gives us the over-all efficiency of the process. 
Thus if we find that by using a certain com- 
bination of coal, furnace, boiler, and engine 
we produce an amount of energy at the belt 
wheel equivalent to 2,545 heat units, and if 
we have burned 4 pounds of coal of 13,000 
British thermal units per pound to do this, 
our input was 4 by 13,000=52,000 British 
thermal units. Our over-all efficiency in this 
case is then 2,545-^-52,000=4.9 per cent, 
and our losses of transformation from 
heat energy to mechanical energy have been 
95.1 per cent of the original heat in the fuel. 
This is a tremendous discrepancy between 
input and output, as well as quite an ordi- 
nary one ; and were it not for our knowledge 
of the principle of the conservation of energy 
we should be able only to grope blindly 



DETERMINING EXISTING LOSSES 11 

toward improvement. We * would have no 
means of knowing in the first place whether 
any improvement were possible, and secondly 
we conld not know in what direction to search 
for preventable losses. 

Bnt fortunately such is not the case. We 
are, on the contrary, able to analyze definitely 
and with satisfaction the entire energy loss 
and to account for each item, and further- 
more to determine what part of the total loss 
is preventable. 

In other words, we can by careful inves- 
tigation and proper tests analyze each step 
of the process of power generation in such 
a. way as to strike a balance with the origi- 
nal input of energy with all items accounted 
for. Then by concentrating our attention 
upon each individual item successively, we 
are able to determine which of them consti- 
tute preventable losses, whereupon they may 
be reclaimed by proper changes in operation 
or equipment and the over-all efficiency of 
the plant will thereby be increased. 

In the days of Watt the power problem was 
one of entire mystery, and improvements 
came slowly by purely experimental hit-and- 
miss methods. The gradual determination 
and gradually increasing application of the 
principles of conservation of energy have 
changed all of this. In 1842 or thereabouts 



12 PREVENTING POWER-PLANT LOSSES 

Joule standardized the mechanical equivalent 
of heat. He found that 772 foot pounds of 
mechanical energy would raise the tempera- 
ture of one pound of pure water one de- 
gree Fahrenheit, which is the unit of heat 
known as the British thermal unit. Later 
experimenters determined this mechanical 
equivalent more accurately to be 778 foot 
pounds. 

By this l i equivalent ' ' we know exactly how 
much loss takes place when we burn so many 
pounds of coal, and produce so many foot 
pounds or horse-power hours of work at our 
engine fly-wheel, for the heat energy of the 
coal is converted by its equivalent to the num- 
ber of foot pounds of energy that would be 
produced at the engine fly-wheel providing 
the process were a perfect one. Then by 
comparing the horse-power hours or foot 
pounds the engine actually does produce with 
the perfect result, we have our percentage 
of efficiency and our percentage of loss. 

When we turn to electrical energy our cal- 
culations just as readily and just as accurate- 
ly translate the scales of our values either 
into those of heat or of mechanical work. 
Thus 1 kilowatt-hour equals 1.34 horse- 
power hours which equals 2,654,200 foot 
pounds or 3,412 heat units. 

Stated in terms of power, which means rate 



DETERMINING EXISTING LOSSES 13 

of work, we have : — 1 kilowatt = 1.34 horse 
power = 3,412 heat units per hour. 

Thus it is seen how readily and accurately 
the entire process of power generation can be 
followed through each successive step from 
the heat units in the coal pile to the final 
amount of mechanical or electrical energy 
which has been the ultimate object of the 
various changes set in motion. 

I have made use of the term "losses'' to 
represent that part of the original energy 
which does not appear at the end of the pro- 
cess as available or useful work for the pur- 
pose in hand. In other words, I have spoken 
of as "loss" the difference between the in- 
put and the output in any power process — 
that is, the discrepancy between 100 per cent 
efficiency and the actual efficiency obtained. 
In the absolute, however, this discrepancy 
or apparent loss is only that part of the origi- 
nal energy which has been absorbed by re- 
sults other than the one desired. A simple 
illustration may be of value. Suppose an 
engine driving the machinery in a shop is 
developing 100 horse power measured at its 
fly-wheel and we find that only 50 horse 
power is reaching the actual machinery. 
Then the efficiency of our transmission is only 
50 per cent and we have a 50 per cent loss 
which is absorbed in friction, a natural cause 



14 PREVENTING POWER-PLANT LOSSES 

capable of absorbing unlimited amounts of 
energy. A part of this loss will probably 
be found to be preventable, say to the ex- 
tent of one-half. Then by reducing the fric- 
tion to this extent by known means of 
transmission improvement, we shall have in- 
creased our efficiency from 50 per cent to 75 
per cent. There will yet be a loss of 25 per 
cent, but we shall have gained 25 -=- 50 or 50 
per cent of available machine power,- or have 
reduced the required engine power by 33 1/3 
per cent for the same machine power. 

It is now seen that while there are no losses 
in nature, at the same time we do find mis- 
directed and misspent energy prevailing 
when we desire to utilize all of it for the par- 
ticular purpose in hand. Also it is true that 
in nearly all cases a part of the wasted en- 
ergy can be recovered and applied to useful 
work. The term "waste energy" is the best 
to apply to what we have termed "loss," and 
helps us to remember the meaning and value 
of the principle of the conservation of en- 
ergy. 

In the practice of fuel economy in the 
boiler plant the first necessity is to determine 
the existing efficiency of operation. It is pos- 
sible and readily practicable to determine 
what percentage of the heat in the coal is 
being converted into heat in the form of 



DETERMINING EXISTING LOSSES 15 

steam in the boilers. The difference between 
the discovered efficiency and 100 per cent is 
the waste of heat (or energy) that is taking 
place. If, for instance, the efficiency is fonnd 
to be 52% per cent, then 47% per cent of the 
heat of the coal is being wasted. An analy- 
sis of each item of this waste may develop 
the fact that 30 per cent of the total heat of 
the coal is escaping np the chimney. A 
further examination may prove that this is 
cansed by the feeding of a large excess of 
air to the fire, and that 17% per cent of this 
is unnecessary and can be stopped by using 
less grate surface and a better method of 
handling fires. In this case the 17% per cent 
of waste heat is added to the old efficiency 
which increases it to 70 per cent. The sav- 
ing in fuel at once becomes 17% zr~ 70 or 25 
per cent and the gain in steam for the same 
coal consumption is 17% -=- 52% = 33 1/3 
per cent. It happens that this example is 
drawn from one of my recent plant investi- 
gations and that the improvement indicated 
was effected without the installation of any 
new equipment whatever. The saving is in 
constant daily operation and is merely typi- 
cal of the application of the principle of con- 
servation of energy to the boiler room de- 
partment of power-plant practice. 

Owners and managers of industrial plants 



16 PREVENTING POWER-PLANT LOSSES 

are frequently confused and often misled by 
the extravagant claims of promoters regard- 
ing the performance of their power contriv- 
ances. It is seldom that such claims are 
made in terms of true efficiency as this would 
at once discredit their statements. An in- 
stance of this Mnd was in connection with a 
smokeless boiler furnace, and purported test 
records were exhibited which showed an 
evaporation of as high as 17 pounds of water 
into steam (from and at 212 degrees) per 
pound of coal. With the best average coal 
obtainable (14,500 B.t.u. per pound) this 
would mean a thermal efficiency of 113.6 per 
cent. That is, they claimed not only the per- 
fect absorption of all the heat the coal con- 
tained but over 13 per cent more. The prin- 
ciple of conservation gave timely warning, 
and shortly afterward I was called upon to 
conduct tests on this furnace which gave very 
ordinary results. 

In summarizing the salient points of our 
introductory discussion we may select the 
following basic features as a foundation for 
subsequent research along the lines of pre- 
ventable losses. 

The determination and location of pre- 
ventable losses offers the most natural and 
logical method of arriving ultimately at in- 
creased efficiency in every field of operation. 



DETERMINING EXISTING LOSSES 17 

In nearly all branches of human endeavor 
there is no proved and universally accepted 
standard which represents ultimate perfec- 
tion or 100 per cent efficiency. Consequently 
there is a lack of the necessary ideal. The 
result of perfect process is unknown. Owing 
to this fact the existing degree of efficiency 
is impossible to determine. Therefore the 
percentage of loss or ivaste is also indeter- 
minable, and improvements are made only as 
a result of more or less blind experimenting. 
Furthermore, after an increase of efficiency 
is so obtained, there is no way of knowing 
how much further improvement is possible. 
This condition baffles research and makes 
progress entirely problematical both as to 
its possibility and as to its extent. All this 
trouble, this blindfolded groping, is due en- 
tirely to our inability to determine the per- 
fect ideal, the mark of final attainment, the 
degree of 100 per cent efficiency. 

In contra-distinction to nearly all other 
fields of research and progress, that of power 
generation and application is imbued by the 
laws of nature with a definite ideal of per-' 
fection beyond which we cannot attain, and 
toward which we may concentrate our efforts 
with the intelligence that our work is truly 
aimed toward the elimination of waste. This 
knowledge is based on the unassailable laws 



18 PREVENTING POWER-PLANT LOSSES 

of the conservation and the transmutation 
of energy. These laws together providing 
an accurate code of measurement of energy 
in its various forms enable the engineer to 
analyze with certainty all of the steps in- 
volved in the liberation, transformation, and 
utilization of energy as applied to the pur- 
poses of power-plant design and operation. 

Just as the expert accountant is able to 
analyze the expenditure of one hundred dol- 
lars in a business enterprise and to show 
where some of them are wasted or misspent, 
and finally to strike a true balance: between 
income and expenditure, just so truly and 
with as great a degree of accuracy a trained 
engineer may analyze and balance the expen- 
diture of energy, from the original 100 per 
cent income or input to the final machine 
horse-power hours of useful work, and in so 
doing he may point out where certain por- 
tions of this energy are misspent or wasted 
and how they may be saved and converted 
into useful work. 

There does not exist a power problem that 
'is not capable of solution by the intelligent 
application of these principles of analysis. 
Furthermore, experience in this special prac- 
tice has demonstrated that preventable losses 
have been found to exist in every power plant 
that has been investigated, and it is some- 



DETERMINING EXISTING LOSSES 19 

what more than probable that they exist to 
greater or less extent in every power plant 
that was ever designed or operated. 

While all types of plants are snbject to 
the investigation and correction of prevent- 
able waste, I shall confine all subsequent sec- 
tions of this treatise to the study of the bet- 
terment of efficiency in factory power plants. 
They not only comprise a very special field, 
owing to particular and varying require- 
ments peculiar to them, but they have re- 
ceived less study and far less attention than 
the more completely developed central power- 
station common to public-service conditions. 
The factory plants are therefore capable of 
far greater improvement, and contain as a 
rule a very large percentage of preventable 
waste which is capable of being converted 
into a handsome profit. The truth of this 
statement will be demonstrated throughout 
this volume, not only by an explanation of 
the method of making investigations but also 
by a citation of typical savings that have 
been the direct result of this work when ap- 
plied to numerous problems in factory 
power plants. 



Chapter II 

ATTAINABLE EFFICIENCY AND OEDINAEY 
WASTES 

/ T S HE local and practical use of the eon- 
-*■ servation principle has resolved the 
work of factory power-plant investigation 
into a definite and at the same time compre- 
hensive code or system. 

The object is to determine not alone the 
over-all efficiency of a plant, but to find out 
the individual efficiency, and conversely the 
waste, of each step in the generation and 
utilization of the energy under consideration. 
Bound up very closely with the practical as- 
pect of the case is the matter of "commer- 
cial efficiency " which always demands the 
most careful investigation. For it is with 
this result that the business man is most 
vitally concerned. He desires to know how 
much he is wasting in terms of dollars and 
cents, and cares very little for this value 
expressed in heat units. He wants to be defi- 
20 



ORDINARY WASTES 21 

nitely informed how many dollars' worth of 
fuel he can dispense with, and not how much 
the combined thermal efficiency of his boilers 
and engines can be increased. 

Commercial efficiency is thermal efficiency 
properly modified by monetary values which 
may be readily applied as demanded by any 
given case. The business man is not very 
much interested, though probably confused, 
by the statement that the internal-combustion 
engine develops a higher thermal efficiency 
than any other kind of prime mover, but he is 
interested in the question as to w r hat kind 
of an engine will produce the greatest num- 
ber of kilowatt-hours for one dollar when 
operating under Ms local conditions and spe- 
cial industrial requirements. Let us take 
an example of commercial efficiency, quite a 
common one. A boiler plant is equipped to 
burn high-grade soft coal of 14,500 B.t.u., 
costing $4 per short ton, at the high efficiency 
of say 75 per cent. (I have tested a well 
equipped plant doing exactly this work in 
every-day practice.) This operation will give 
1,000 pounds of steam at a fuel cost of 
$0.1785. 1 

0.75 X 14,500 = 11.2 pounds. 

1 Evaporation per pound of coal = 

970.4 
That is 75 per cent of the heat value of the coal (14,500 B.t.u.) is utilized, 
and a pound of water is evaporated into steam from and at 212 degrees for 
each 970.4 B.t.u. so utilized. This last figure is the unit of evaporation, 
and is the amount of heat required to gasify a pound of water under these 



22 PREVENTING POWER-PLANT LOSSES 

Now if there happens to be in the market 
a poorer grade of coal of 12,000 B.t.u., which 
it is known will develop raider equally favor- 
able conditions an efficiency of only 68 per 
cent hut costing only $2.00 per ton, the fuel 
cost of evaporation may be made by its use 
$0,119 per 1,000 pounds of steam. 2 There- 
fore we may reduce our thermal efficiency 
and at the same time increase our commer- 
cial efficiency enough to gain a fuel-cost sav- 
ing of 



/0.1785— 0.1190\ 
^ 01785 ) 



-33 1/3 per cent 



If we know the two thermal efficiencies and 
their respective coal prices, we may deter- 
mine a true comparison of commercial ef- 
ficiencies by application of a very simple 
formula, retaining the present existing ther- 
mal efficiency as a basis. This formula is as 
follows : 

Commercial Efficiency = 

(B.t.u.2 X Pricei) 



Ec 



(B.t.u.i X Price 2 ) 



conditions without loss. The fuel cost of evaporating 1,000 pounds of 

1,000 $4.00 

water will be in this case X ■ = $0.1785. 

11.2 2000 

0.68 X 12,000 

1 Evaporation = = 8.4 pounds and fuel cost of 1,000 

970.4 

1,000 $2.00 

pounds steam = X = $0,119. 

8.4 2,000 



Ordinary wastes 23 

In which: — 

Ec = the new thermal efficiency under consid- 
eration. 

B.t.u.i = the heat per pound of coal now 
burned. 

B.t.u.2 = the heat per pound of coal proposed. 

Pricei = cost per ton of coal now burned. 

Price 2 = cost per ton of coal proposed. 

The commercial efficiency thus obtained is 
directly comparable to the original thermal 
efficiency of the boiler plant. 

This emphasizes one of the practical appli- 
cations of commercial efficiency. It will be 
noted,_ however, that a knowledge of thermal 
efficiency is at the foundation of the commer- 
cial value and is essential to it. 

There are many other instances of the 
modification or translation of thermal effi- 
ciencies to meet financial requirements. One 
of the more important of these is the matter 
of determining the net financial returns con- 
nected with a proposed change. Thus under 
a given set of conditions it may be found 
that a certain device will save a definite per- 
centage of the coal fired under the boilers. 
It is self-evident that if such a device is suf- 
ficiently expensive in first cost or in opera- 
tion, the return on the investment will not 
warrant its installation. Also an accurate 
deduction must be made from the apparent 
saving to cover all fixed charges necessitated 



24 PREVENTING POWER-PLANT LOSSES 

by the proposed change. These charges must 
always include the items of interest, depreci- 
ation, repairs, added labor, and sometimes 
insurance, and the consideration of safety 
and reliability must never be neglected. 

In other words, the true commercial sav- 
ing to the plant owner is the annual gross 
saving of the device less all yearly charges 
of all kinds that would result from its pur- 
chase and use. 

There have been cases in my experience 
where for instance an improved type of steam 
engine would reduce the consumption of 
steam and fuel, but where cheap fuel was 
burned so efficiently that at the consequent 
low cost of steam the saving in dollars per 
year would not have paid a good interest 
upon the cost of the change. 

It is a fact, however, that in most factory 
plants savings can always be made which 
will pay for themselves, all charges included, 
within two or possibly three years, after 
which the savings are clear profit. In a 
great many cases the possible savings re- 
vealed by scientific investigation are so large 
that they will pay for themselves in one 
year and often in a few months. 

" Power costs" are entirely a matter of 
commercial efficiency, remembering always 
that commercial efficiency is derived from 



ORDINARY WASTES 25 

thermal efficiency properly modified with 
monetary values suited to any given set of 
local . conditions. It may be said that the 
cost of power depends upon two factors, viz : 
— thermal efficiency and location; for the 
location always determines the cost and qual- 
ity of fuel, of labor, and of equipment as well 
as the value of money. 

I have said that the principle of the con- 
servation of energy has enabled us to reduce 
the matter of power-cost investigation to a 
definite scientific system. This system, as 
just pointed out, has two factors, viz: ther- 
mal efficiency and monetary value, the two 
combined producing the ultimate commercial 
efficiency of the sought for result. I have 
no doubt sufficiently indicated the method of 
converting thermal efficiency into commercial 
efficiency, a purely arithmetical operation 
providing ample consideration is given to all 
entering conditions ; and I will now pass on 
to an explanation and discussion of the un- 
derlying chain of thermal efficiencies which 
constitute the foundation of economy. 

For the sake of clearness in this undertak- 
ing I will take an example of what may be 
considered a typical factory power plant. 

During the present stage of our develop- 
ment steam power is employed in the great 
majority of factories. There are sound rea- 



26 PREVENTING POWER-PLANT LOSSES 

sons for this as well as for the prediction that 
steam will continue well into the future as 
the one greatest source of power for onr in- 
dustries. Therefore we shall select a steam 
plant for our illustration of factory power- 
plant analysis. The degrees of efficiency of 
the various parts of our plant will be selected 
as a fair average of the existing conditions 
of the times. 

The boiler plant generally delivers a part 
of its steam to engines and pumps and the 
remainder to heating systems and process 
work. The exact distribution of this steam 
is determined by special tests made for the 
purpose, and as illustration I have selected 
a simple "Steam Balance" from one of my 
reports on a factory boiler plant. 

STEAM BALANCE FOR BOILER ON 8-HOUR BASIS FROM 
7 A. M. TO 3 P. M. 

Average boiler horse power developed with full 

working load 222 

Average boiler horse power used by main 

engine 131 . 

Average boiler horse power used by one 

feed and one vacuum pump . 14 . 2 

Average boiler horse power used by first 

coat dry room 41.0 

Average boiler horse power tol 
printing engines | 

Oil-pumping engine j* by diff . 35 . 8 

Low - pressure boiler - feed 

pUmp J 

Total outputr 222.0 222 



1 2 

» Hi 

S 8g 






ORDINARY WASTES 27 

While these several uses of the steam are 
closely inter-related in their bearing upon 
our problem in general, it will facilitate 
analysis to treat these two methods of con- 
sumption in separate though parallel divi- 
sions. For the sake of clearness therefore 
the accompanying series of diagrams has 
been arranged to illustrate a plant in which 
all the steam from the boilers goes directly 
to the engines and no live steam is used for 
heating. (See insert facing this page.) 

We have now seen a graphic illustration 
of the complete cycle and distribution of 
steam such as would be actually found in 
what may be truly said to be a typical fac- 
tory power plant, providing all the steam 
from the boilers first entered the engines. 
Usually, however, a considerable portion of 
this original steam goes directly to heating 
and process work. In this case its cycles 
of utilization, waste, and return can be traced 
and measured in the same way that has just 
been illustrated in the case of the exhaust 
steam. This will be treated in the chapter 
on heating. 

It will be noted that one item of our en- 
ergy has not yet been followed through to 
the end, and that is the portion of heat en- 
ergy which was converted into useful me- 
chanical work by our steam engine. There 



28 PREVENTING POWER-PLANT LOSSES 

are two common methods in factory power 
plants for the distribution of this energy: 1, 
direct mechanical transmission, by shafting 
and belting or rope drive; and 2, electrical 
transmission, which also involves usually a 
certain amount of mechanical transmission. 

Now since there is a vast amount of con- 
fusion as to the relative advantages of these 
two methods and regarding the controlling 
factors, we shall examine into both systems 
with an illustration of each, together with 
their respective attendant losses and efficien- 
cies. Before proceeding, however, let it be 
clearly stated that there is no prima facie 
reason for expecting great differences in ef- 
ficiency from either system, but that the ad- 
vantages of one over the other depend en- 
tirely upon local circumstances. As will be 
shown in our illustration, for every loss in 
mechanical transmission there is a corre- 
sponding loss in electrical transmission, and 
the particular conditions surrounding any 
given case will alone determine the advan- 
tages of the one over the other. Such ad- 
vantages, it is true, may at times be very 
great indeed, but so much misinformation at 
present exists among the laity on this sub- 
ject that a pair of analyses will be of ser- 
vice. 

Eeferring now to our foregoing diagrams 



Ordinary wastes 29 

of heat and steam distribution it will be re- 
membered that only 7.3 per cent of the heat 
in the steam supplied to our engine was con- 
verted into mechanical energy or work. We 
have seen what in part became of the balance 
of the original supply of heat or energy from 
the coal pile, but at present our interest is 
confined to this 7.3 per cent of the heat of 
the steam which we now have in the form 
of work at our engine shaft. During our 
inspection of these examples of transmission 
it must be- remembered that the variations 
in efficiency of either system under different 
conditions of operation and design are very 
great, and these cases are selected simply for 
the purpose of tracing their processes of ef- 
ficiency and loss in a manner that is con- 
stant qualitatively but extremely variable 
when quantitatively considered. 

For both cases we have at the engine shaft 
7.3 per cent of the heat energy of the steam 
entering the engine, which represents an 
over-all efficiency of 4.16 per cent referred 
to the original heat in the coal. For clear- 
ness of analysis consider the energy at the 
engine shaft 100 per cent. 

The analyses on pages 30, 31 give a fair 
representation of power distribution and loss 
on a percentage basis of the full or constant 
output of the main engine. Now while this 



30 PREVENTING POWER-PLANT LOSSES 

analysis holds true qualitatively at all times, 
yet there may be savings possible with an 
electrical system in cases where its use will 
enable the complete shutting" down at times 
of departments of a factory for which other- 
wise it might be necessary to run long and 
heavy line shafts continuously, irrespective 
of actual power required. 

On the other hand, if all machinery is to 
be run at full capacity continuously, in the 
case we have analyzed electrical transmis- 
sion would save no steam at the engine nor 
any coal in the boiler room. This whole mat- 
ter is capable of computation for any given 
set of conditions in advance of making con- 
templated changes; and in such calculation 
(.which should be based upon actual test 
data) the cost factors must be carefully ap- 
plied in order to learn the true commercial 
efficiency of the undertaking. 

COMPARATIVE ANALYSIS OF MECHANICAL AND ELEC- 
TRICAL POWER DISTRIBUTION AND LOSSES 

Mechanical Transmission 

At engine shaft 100 

Efficiency of main belt . 97 

Loss at main belt . 03 

Delivered at line shaft 97 

Efficiency of line shaft . 85 

Friction of line shaft 0.15 

Delivered at countershafts 82 . 5 



ORDINARY WASTES 31 

Efficiency of other shafting and belting. . 88 
Friction of other shafting and belting. . 0. 12 

Delivered at machines 72 . 6 

Energy delivered at machines 72.6 per 

cent X 4.16 per cent =3.02 per cent 

of the heat in the coal. 

Electrical Transmission 

At engine shaft 100 

Combined mechanical and electrical effi- 
ciency of dynamo . 90 

Loss at dynamo --. 0.10 

Delivered on switchboard 90 

Efficiency of electrical mains . 98 

Resistance of mains . 02 

Delivered at motors 88 . 2 

Efficiency of motors . 88 

Mechanical and electrical loss in motors. . 12 
Delivered at machines or short countershafts. 77.6 
Efficiency of countershafts and belting 

on groups of machines . 92 

Friction on countershafts and belting 

on groups of machines . 08 

Delivered at machines 71.4 

Energy delivered at machines 71.4 per 
cent X 4.16 per cent = 2.97 per cent 
of the heat in the coal. 

The principal teaching of our discussions 
thus far, however, is that we are able to 
analyze each successive step in the genera- 
tion and utilization of energy in the factory 
power plant. The methods of performing 
this analysis will be discussed later, and it 
will be shown not only how we may actually 
determine the over-all and the individual ef- 



32 PREVENTING POWER-PLANT LOSSES 

ficiencies and losses in onr processes, but 
the investigation of the preventable losses 
will be taken np in detail. 

For the present let ns realize, if we can, 
that no energy is really lost — it is only mis- 
directed; that the principle of the conserva- 
tion of energy as pointed out in our first 
chapter is a practical theory, and constitutes 
the very foundation of our present-day prac- 
tice of power-plant investigation and im- 
provement. 

We have seen in the foregoing analyses 
that each successive stage in the chain of 
conversions and transmissions of energy has 
an individual efficiency of its own, and that 
the ultimate efficiency at the end of the chain 
is only the product of them all. Consequently 
it follows that a high ultimate efficiency can 
be obtained only from a thorough study of 
the individual efficiencies. The improve- 
ment that may be possible depends upon the 
percentage of preventable loss in each of 
these steps or stages. The loss, or rather 
waste, in each step of conversion or trans- 
mission is simply the difference between 100 
per cent and its determined efficiency. The 
energy which constitutes this waste is all 
used in ways that can be determined, both 
as to location and extent. It is not lost ex- 
cept in so far as it affects the efficiency of 



ORDINARY WASTES 33 

our plant. Since it is not lost, it can be 
traced and measured and analyzed by appli- 
cation of scientific knowledge. When thus in- 
vestigated, that part of the waste which is 
preventable can be determined, and the cause 
being also definitely learned it can be elimi- 
nated, with the result that this preventable 
portion is saved and added directly to in- 
crease the old efficiency. 

Now our general view of the operation of 
the typical factory power plant has brought 
out a number of facts which will guide us 
toward a logical method of investigation. 
Some of the more important of these fea- 
tures are here enumerated. 

1. The correction of a preventable waste 
in the boiler plant resulting in a given per- 
centage of fuel saved will, from a fuel stand- 
point, affect the whole cost of power and 
heating throughout the plant to the extent 
of this percentage. This fact is independent 
of any proportion of the boiler steam that 
may be used direct for heating or process 
purposes, and renders an investigation of the 
boiler room of primary importance. Further- 
more, the waste in our average boiler plant 
is very great, 42 per cent of the heat in the 
coal, and it may be added that a large part 
of this waste is preventable. Thus it is 
possible and practicable to operate a factory 



34 PREVENTING POWER-PLANT LOSSES 

boiler plant at 70 to 75 per cent efficiency. 
In the latter case we should be able. to add 
17 per cent of the 42 per cent waste to the 
58 per cent efficiency, and the result would 
be 17 -f- 58 = 29.3 per cent more steam for 
the same fuel, or for the same steaming ca- 
pacity as before a saving in fuel of 17 -f- 75 
= 22.7 per cent. 

A plant owner who was retaining me to 
investigate his fuel problem, said "We can 
see just where our principal loss is. Those 
drips from our heating system are not re- 
turned to the boilers and that means a large 
waste." As a matter of fact the drips he 
referred to were from a heating system which 
condensed possibly one-third of his boiler 
steam. The drips at 180 degrees would con- 
tain 120 B.t.u. per pound or 40 B.t.u. per 
pound of steam at the boilers. Since a pound 
of his boiler steam contained 1,150 B.t.u., the 
return of these drips would represent a sav- 
ing of only 40 -f- 1,150 or about 3% per cent 
of his coal bill. 

He was making the common mistake of 
beginning his investigation at the tail end 
of the problem instead of starting in at the 
source of all his power and heating, the boiler 
plant. Upon centering the investigation at 
this point a preventable loss of 30 per cent 



ORDINARY WASTES 35 

of the entire coal pile was located and cor- 
rected. 

This incident is quoted merely to illus- 
trate the principle involved in the logical 
method of attacking the factory fuel prob- 




Fig. 8. Distribution of Boiler Output 

lem. From the boiler plant as a centre and 
source, the uses and wastes of steam radi- 
ate outward like the vanes of an open fan, 
each blade or group of blades representing 
the proportion and consumption of steam in 
each department. 

Figure 8 illustrates this, the black sector 
representing the entire output of the boilers. 



36 PREVENTING POWER-PLANT LOSSES 

Thus if we find a means of saving say 15 per 
cent of the "live steam," which in the illus- 
tration represents about 25 per cent of the 
total boiler steam, our saving will not be 15 
per cent of the coal bill, but only 15 per cent 
of 25 per cent, or less than 4 per cent at the 
source of heat. 

Thus are we enabled to see clearly why 
it is of first importance to subject the boiler 
plant to the most thorough and exhaustive 
investigation, and furthermore why this de- 
partment should logically come first for our 
consideration. 

2. The second fact of importance made 
clear by our general view T of the problem as 
a whole is in connection with the very low 
efficiency of our steam engine. In the ex- 
ample quoted a simple Corliss engine has 
been selected as representative of general 
factory conditions, and 7.3 per cent thermal 
efficiency is a fair working average of the 
performance of this type. In this case our 
engine is run non-condensing and the ques- 
tion of the comparative economy of con- 
densing naturally arises. We have seen that 
of the total heat that enters the throttle of 
our engine over 90 per cent escapes through 
the exhaust pipe. At what point will it pay 
to install a condenser, in order to improve 
the thermal efficiency of our engine as related 



ORDINARY WASTES 37 

to the other expedient of better utilization of 
its exhaust heat? Why not put in a steam 
engine of the most economical type with the 
best kind of condensing equipment, and heat- 
our factory with steam from a separate low- 
pressure boiler? What would be the result 
of this plan? Would it be best to throw out 
the steam engine entirely and substitute an 
oil engine, a producer-gas plant, or current 
purchased from a water-power or central- 
power plant? 

What are the efficiencies of other prime 
movers compared to the steam engine? If 
they are better why not use them? A hun- 
dred and one questions like these, and more, 
arise from our look into the heat efficiency 
of the steam engine. And these questions 
thus inspired form the raison d'etre of the 
great field of applied science comprising this 
department of our problem, second only in 
importance to the boiler plant. 

3. We have noted, to the surprise of some 
of us no doubt, the tremendous amount of 
heat contained in the exhaust steam, al- 
though its pressure has been reduced from 
101.3 pounds to 5.3 pounds and during this 
fall in pressure has developed the full horse 
power of our engine. We have seen that 
our plant is blowing away about half of this 
valuable by-product of the steam engine, and 



38 PREVENTING POWER-PLANT LOSSES 

of the other half only a fraction is utilized 
by the heating system into which it is fed. 
Here, indeed, are very great losses vitally 
affecting the consumption of fuel at the boiler 
plant. 

We have seen that steam at the low pres- 
sure contains within 2 per cent as much heat 
as steam at 101-pounds pressure, disregard- 
ing the effect of the engine; and when the 
engine is included we still have some 90 per 
cent of the original heat of the steam in the 
form of exhaust. 

This being true, why not cut out live steam 
entirely and substitute exhaust from the en- 
gine? A great saving may result from this 
measure if conditions permit. What then, 
are these limiting conditions'? When by- 
product exhaust steam is worth practically 
as much as expensive live steam direct from 
the boilers, it is reasonable to assume that 
a complete knowledge of the characteristics 
of exhaust steam and of the factors connected 
with its utilization must constitute a most 
important element in our ultimate efficiency 
and consumption of fuel. This in fact is so 
emphatically the case that the successful so- 
lution and minimum cost in many a factory 
power plant hinge directly upon the skillful 
handling of this feature of the problem. 

So closely connected with this matter that 



ORDINARY WASTES 39 

it cannot be separated from it is the efficiency 
factor of the heating system for buildings 
and process work. Our typical analysis has 
shown a waste of 70 per cent in the use of 
steam in the heating system. We have also 
seen where this waste goes and how small 
a part of it is returned to the boilers. There- 
fore a careful study of preventable losses in 
heating systems is essential, and since these 
losses or wastes are measurable, as w r ell as 
the utilized portion of the energy, we are 
able to grasp the problem with the simplicity 
of directness. This advantage is character- 
istic of our whole problem since it is com- 
pletely governed throughout by the very 
beautiful and satisfying laws of the conser- 
vation of energy. 

We have now a fair inkling of the under- 
lying philosophy of power-plant investiga- 
tion. I have stated that this philosophy has . 
naturally evolved an efficient method for at- 
tacking any given problem, so that perhaps 
the next logical step in our discussion will 
be the statement of this method which is com- 
prehensive for any given case. 

Again, for the sake of clearness, a steam 
plant will be taken for an example, rather 
than risk possible confusion by an attempt to 
make statements both broad and definite 
enough to cover all cases. Let it be under- 



40 PREVENTING POWER-PLANT LOSSES 

stood, however, that the principles involved 
completely cover all imaginable types of 
power and heating plants. 

Plan of Factory Power-Plant Investiga- 
tion 

1. Boiler Plant. Tests under actual work- 
ing conditions will reveal the following in- 
formation. 

Combined Efficiency of boiler and furnace 
and a comparison of this efficiency with what 
they would develop under right conditions of 
operation and equipment. 

Evaporation per Pound of coal as fired, of 
dry coal and of combustible. 

Cost of Fuel for evaporating 1,000 pounds 
of steam. 

Capacity of Boilers, i. e., horse power ac- 
tually developed compared to their rated ca- 
pacity or heating surface, showing whether 
boilers are over- or under-loaded for best 
economy. This will show whether the right 
number of boilers are being operated, 
whether too many or too few for lowest coal 
consumption. 

Number of Heat Units in a Pound of Coal, 
ash, moisture, etc. 

Total Waste of Heat of Coal. This is ob- 
tained by taking chemical analyses of the 



ORDINARY WASTES 41 

gases resulting from its combustion, together 
with temperature of these escaping gases 
and of the air in the fireroom, and with an- 
alysis of the coal and other test data. 

Heat Balance. A definite accounting of 
the expenditure of all the heat in the coal con- 
sumed. Thus the Efficiency is the percentage 
of this heat absorbed by the boiler and con- 
verted into steam. The balance of heat is 
then accounted for item by item to make up 
the full 100 per cent. 

Load Fluctuation. As affecting type of 
boilers, kind of coal, and design and opera- 
tion of furnaces. 

Preventable Waste. An examination of 
the heat balance shows exactly what portion 
of the total waste may be reclaimed and 
added to the efficiency. Such portion may be 
collectively caused by excessive radiation, 
unburned or partially burned combustible, 
excess of air supply to the fires, leakage of 
cold air through setting, loss of carbon 
through grate or through cleaning opera- 
tions, each one of which effects has a direct 
cause which can be eliminated through 
changes in either operation or equipment, 
and generally largely through the former. 
The special local causes producing these 
losses may be determined for elimination. 



42 PREVENTING POWER-PLANT LOSSES 

Cost of Evaporation with some other or 
cheaper kind of coal. Adaptability of pres- 
ent equipment for such change and its at- 
tendant cost of installation and equipment. 
This includes an investigation of all coals 
on the market, taking reliability of supply 
and fluctuation of prices into consideration, 
as well as any possible additional cost of fir- 
ing or ash handling. 

Coal and Ash Handling. An examination 
of this subject under local conditions with 
respect to the possibility of reducing cost of 
the work. 

Finally, Becowimendations Jbased upon the 
complete finding of the boiler-plant investi- 
gation may be made in such manner that the 
maximum commercial saving which can be 
accurately predicted will result from their 
execution. 

2. Steam Piping. The heat and fuel loss 
due to badly designed or uncovered steam 
piping are calculated accurately, with esti- 
mate of financial saving possible by improve- 
ment in these respects. Also economy due 
to safety of properly arranged steam piping, 
protection of engines from water, etc. Safety 
to operatives as well as plant depend upon 
safe boiler and engine piping and precaution 
against accident. 



ordinary wastes 43 

3. Engine Plant. 

Test to Determine Efficiency of Engines, 
amount and cause of waste, including: — 

Steam Consumption per Horse-power or 
Kilowatt Hour compared to good normal 
consumption for the particular type of equip- 
ment. If below this efficiency the amount of 
preventable loss is known, and its location is 
determined by indicator and leakage tests, 
as well as friction and back-pressure tests on 
the engine and efficiency test on the electric 
generator if one is driven by the engine. 

Thus the amount, location and cause of the 
preventable losses are discovered and correct 
remedy can then be definitely recommended. 

Any saving that might be possible by sub- 
stituting a more efficient type of engine will 
now be calculable, the possible use of ex- 
haust steam to figure in this consideration. 

Fuel Cost per Horse-Power or Kilowatt 
Hour can now be obtained (the boiler test 
having been made) and should be decreased 
by a true allowance for any part of the ex- 
haust steam from the engine which is tak- 
ing the place of an equivalent amount of live 
steam that would otherwise be required. 

Value of Condensing versus Non-Condens- 
ing is definitely estimated with consideration 
of all surrounding and local conditions. 



44 PREVENTING POWER-PLANT LOSSES 

Boiler Pressure as affecting engine econo- 
my accurately calculable. 

Superheating steam at boilers or with 
separately fired superheater investigated for 
local conditions and thermal and commercial 
efficiencies decided with proper consideration 
of design and construction of engines and 
piping and percentage of boiler steam to en- 
gines or carried long distances. Effect upon 
dryness of exhaust steam with bearing on 
heating. 

Determination of relative values of high-, 
low-, or mixed-pressure turbines, compound 
or simple engines, etc., for the local require- 
ments. 

Day and Night and Summer and Winter 
Loads as affecting number and type of en- 
gines. 

Recommendations. These are made only 
after investigation of both boiler plant and 
heating system. 

4. Heating System, including steam for 
process work. 

Determination of that Part of Boiler Steam 
at present used direct. 

a — For heating, day and night, summer 
and winter. 

b — For process, day and night, summer 
and winter. 



ORDINARY WASTES 45 

Determination of that Part of Boiler Steam 
which goes to engine and pumps. 

Determination of that Portion of Exhaust 
Steam which is efficiently utilized and that 
part which is wasted. 

Amount of Direct Steam that could be re- 
placed by exhaust now available, or which 
could be made available and commercial 
economy of such change worked out. 

Efficiency of Present Heating System as 
found, and amount of preventable waste re- 
ferred to coal consumption. 

Crediting to engine performance that por- 
tion of their heat given to the heating sys- 
tem, as affecting cost of fuel for power only. 

Recommendations on Heating based not 
only on separate investigation of same but 
also as influenced by the result of examina- 
tion of Boiler and Engine questions as per 
previous headings. 

5. Cost of Power. This is of especial im- 
portance when a proposition for buying elec- 
tric current from central or water-power 
station demands consideration. The full data 
obtained on boiler plant, engines and heating 
enable an accurate determination of power 
cost per kilowatt or horse-power hour by 
combining such data with full operating 
costs which include labor, repairs, interest, 
depreciation and insurance. The utiliza- 



46 PREVENTING POWER-PLANT LOSSES 

tion of exhaust steam is a large factor in 
this result. 

Present Cost of Power determined as 
above. 

Reduction in Existing Cost of Power. 
The amount by which this present cost per 
kilowatt or horse-power hour can be reduced 
depends entirely upon the information re- 
garding preventable waste throughout the 
whole plant as determined by the foregoing 
investigation. 

The cost of making the plant efficient 
should be added as an interest charge, and 
then this new cost of power that can be pro- 
duced in the improved factory power plant 
is directly comparable to the cost of current 
as offered by the electric company, provid- 
ing certain charges connected with the price 
per kilowatt-hour of the latter are added to 
it for a just comparison. 

Thus it is practicable to determine precise- 
ly for any given factory power plant at what 
price it will pay to contract for the purchase 
of outside electric power. 

We have seen that the science of power- 
plant improvement depends upon the princi- 
ples of the conservation of energy, that the 
logical application of these laws has evolved 
a normal and comprehensive method for the 
determination and measurement of prevent- 



OEDINARY WASTES 47 

able fuel waste; and in accordance with the 
method thus developed we shall now consecu- 
tively consider the individual efficiencies 
constituting the complete cycle which we 
have graphically illustrated, whose com- 
bined product constitutes the ultimate effi- 
ciency of our factory power plant. In this 
proceeding our object will be not only to de- 
scribe the theory of testing each of these 
specified efficiencies, but also to give exam- 
ples of such tests taken from actual reports 
of this nature and to show in a practical man- 
ner some of the resultant losses that are thus 
determined together with the means for their 
correction. In this treatment the boiler 
plant will logically receive our first attention, 
and since instances from actual investiga- 
tions will be quoted commercial efficiency will 
be seen to be the ultimate object of the work 
throughout. But it will be equally apparent 
that the necessary and only available means 
for a complete knowledge of this financial 
value is the determination of thermal ef- 
ficiency in accordance with the laws of the 
conservation of energy. 



Chapter III 
THE BOILER PLANT 

INVESTIGATIONS for determination of 
-■- waste in the boiler plant must not only 
be made in such a manner that the efficiency 
and losses of operation will become known, 
but they must be performed with such thor- 
oughness that the exact* location, cause, and 
extent of the preventable portion of all losses 
will be made evident. 

Furthermore, the preventable losses must 
be determined with equal thoroughness from 
the standpoint of commercial efficiency. All 
these desirable results can be obtained. 
Furthermore, they are obtained in actual 
practice, and without disturbance to the regu- 
lar operation of the plant. They are natu- 
rally followed by improved efficiency and a 
reduced cost for steam, since the existing 
faults are definitely determined and meas- 
ured, eliminating all guess work in the recom- 
mendation of proper means for their correc- 
48 



THE BOILEK PLANT 49 

tion. It requires no stretching of the truth 
to say that boiler-plant improvement by this 
method of investigation becomes an exact sci- 
ence, and one of great practical value. 

After getting acquainted first with the ex- 
ecutive and operating members of the boiler- 
plant department, the investigator makes ar- 
rangements for conducting boiler tests which 
shall give the results of an average per- 
formance of the boilers and furnaces under 
average working conditions. The chief en- 
gineer is requested to urge upon his firemen 
that they shall pay no attention whatever 
.to the boiler testing but shall perform their 
duties in their accustomed everyday fashion. 
This is very important ; for if, as sometimes 
happens, the firemen receive the impression 
that they are in some way being spied upon, 
they will try to make a record during the 
test, in which case the results will usually 
be above the average of daily practice. If 
through neglect of the proper precautions 
this should happen, it alters the test results 
and the determination of preventable waste. 
But even in this circumstance, the difference 
in the calculations of the expert is on the 
safe side. That is to say, if the plant is 
operated at higher than usual efficiency, the 
possible savings predicted by the investiga- 
tor will be proportionately smaller, so that 



50 PREVENTING POWER-PLANT LOSSES 

when his recommendations are put into ef- 
fect the actual savings thereby produced will 
be larger than his original estimate. This, 
however, is not desirable and the necessary 
precaution should be observed for the pre- 
vention of its occurrence. 

As a further preliminary measure, the ob- 
ject and method of the whole investigation 
should be fully explained and discussed with 
the operating engineer. When he is the kind 
of man who is truly interested in the effi- 
ciency of his company's plant and is ambi- 
tious for his own mental and pecuniary ad- 
vancement, he will be anxious to aid in the 
work and to gain all the knowledge and in- 
formation from the tests that he possibly 
can. If ocasionally this is not the case, then 
appropriate measures are required according 
to the circumstances. 

Since combustion consists of a chemical re- 
action of gases and elements with the oxygen 
of the air, the efficiency of its operation is 
not visible to the eye. The steam gas in 
the boilers which is the object of the com- 
bustion is also invisible. Consequently the 
average factory-plant management is quite 
at sea regarding the efficiency of its boilers 
and furnaces, even though it may be very 
modern in its efficiency methods when deal- 
ing with the processes and products of the 



THE BOILER PLANT 51 

manufacturing departments. The efficiency 
of a boiler plant is a hidden matter. It lies 
beneath the surface. Nothing less than a 
scientific test will reveal the usually great 
losses that are taking place. These losses, 
which are largely preventable, are quite in- 
dependent in any degree of the external ap- 
pearance of the equipment itself, and such 
matters as white-tile finish and polished 
brass are frequently and justly comparable 
to the "goodly apple rotten at the core". 
In one manufacturing plant which I investi- 
gated the boiler house was its particular 
pride and joy, and no suspicion had rested 
upon it as the possible source of a great 
waste which baffled the owners. The plant 
was indeed pleasing to the eye in every par- 
ticular, but when subjected to test exhibited 
a very different aspect from the pocket-book 
point of view. The boilers were found to 
be developing only half of their rated capac- 
ity, and although the total requirements were 
only in the neighborhood of 600 horse power 
the commercial-efficiency test discovered a 
preventable loss of $7,000 per year in fuel 
expense. 

In addition to the necessity of boiler test- 
ing, this example suggests the value of plac- 
ing a plant under a strict efficiency system 
which shall daily reveal to the management 



52 PREVENTING POWER-PLANT LOSSES 

the economy of its operation. This feature 
will be carefully treated in its proper place. 

Very frequently unreliable reports are 
made as to the performance of boilers, and 
large indeed is the number of false or mis- 
leading statements of this kind. The aver- 
age layman accepts as criterion a statement 
or determination of "water evaporated per 
pound of coal". He makes no distinction be- 
tween actual evaporation and equivalent 
evaporation from and at 212 degrees. These 
different ways of reporting a test may af- 
fect the resulting figure as much as 20 per 
cent, and if the business man is not sure 
of how his test was made and just what the 
figure means, he would do well to avoid what 
may prove to be an expensive mistake by 
taking the wise precaution of finding out. 

Still another common error, and as seri- 
ous a one, consists in taking the figures which 
represent evaporation per pound of combus- 
tible for the evaporation per pound of coal. 
This leads to much trouble because coal and 
combustible are not the same thing. The 
combustible portion may be only 80 per cent 
of the weight of the coal. Consequently the 
evaporation based on combustible is always 
a correspondingly higher figure than that 
based on the coal. Furthermore, there are 
two ways of reporting the amount of com- 



THE BOILEll PLANT 53 

bustible, the chemical and the mechanical, 
each with its own result. Consequently 
when we consider "actual" evaporation and 
"equivalent" evaporation as each being com- 
monly referred both" to coal and to combusti- 
ble, we have four correct though incomplete 
methods of stating boiler results. Add to 
this the fact that the amount of combusti- 
ble is obtained in the two different ways just 
mentioned, and we have six different meth- 
ods of reporting evaporation. There are 
still two more ways, viz : actual and equiva- 
lent evaporation individually based on the 
coal as fired, which contains moisture some- 
times as much as 10 per cent, altering the 
results and their significance to a marked 
degree. 

Enough has been said on this point to in- 
dicate the trouble which managers are likely 
to have in understanding and interpreting 
correctly the value and meaning of the term 
' ' evaporation ' '. And yet it remains true that 
when in some manner they have obtained 
a single one of the numerous evaporation 
figures from their boiler plant, they frequent- 
ly imagine that they know the degree of 
economy with which their boilers are work- 
ing. But as a matter of fact they have no 
such knowledge, even if the determination 
is entirely correct, which is seldom the case. 



54 PREVENTING POWER-PLANT LOSSES 

For the economy indicated by an evaporative 
result depends entirely upon the heat value 
of the fuel. Thus an "equivalent" evapora- 
tion of 8 pounds based on dry coal will repre- 
sent the fairly high boiler and 'furnace ef- 
ficiency of 70.5 per cent if a pound of the coal 
contains 11,000 heat units; but the same 
evaporation with a coal of 14,500 B.t.u. will 
exhibit the poor efficiency of only 53.5 per 
cent, a vast difference indeed. And so the 
evaporative result of a boiler means nothing 
whatever as indicative of its efficiency unless 
the heat value of the fuel be taken into our 
calculation. Now, by referring to previous 
chapters it will be remembered that efficiency 
is always the useful output of energy (or 
heat) compared to the input, i. e., Output 
-f- Input = Efficiency. In the case of our 
boiler and furnace the heat in a pound of 
coal represents the input and the heat in the 
steam generated by each pound of coal is the 
output. Now the heat put into a pound of 
steam varies with the temperature of the 
feed water and the pressure of the steam in 
the boiler. For convenience and uniformity 
of expression, mechanical engineers have 
adopted a unit of evaporation which is sim- 
ply the amount of heat that is necessary to 
evaporate a pound of water from a feed- 
water temperature of 212 degrees into steam 



THE BOILER PLANT 55 

at the same temperature and the correspond- 
ing or atmospheric pressure, and this actual 
amount is 970.4 heat units (B.t.u.). Conse- 
quently, by a simple calculation involving the 
factor of evaporation, all actual evapora- 
tions under varying temperatures and pres- 
sures are reduced to their equivalent evapo- 
ration from and at 212 degrees, and each 
pound of equivalent evaporation represents 
970.4 B.t.u. 

Thus the efficiency of a boiler and furnace 
is determined by dividing the " output' ' or 
pounds of equivalent evaporation, multiplied 
by 970.4 B.t.u., by the B.t.u. in a pound of 
coal producing that evaporation. 1 With cor- 
rect data in hand it is therefore a simple 
matter to obtain the efficiency of our boiler 
plant, and when thus obtained it forms a true 
and the only true measure of economy. 

Irrespective of the value of the coal, the 
pressure of the steam, the temperature of 
the feed water, the kind of apparatus, and 
of any and all conditions whatsoever, the 
thermal efficiency of the boiler and furnace 

1 The factor of evaporation is found for a given combination of steam 
pressure and feed-water temperature by dividing the actual heat in a pound 
of this steam above its feed temperature by 970.4. Thus the formula 
becomes: 

F == (H — h) -=- 970.4 in which 
H = total heat in the steam above 32 degrees at the operating pressure; 
h = total heat in the feed water above 32 degrees; 970.4 = latent heat 
of evaporation at 212 degrees; F = the factor of evaporation. 



56 PREVENTING POWER-PLANT LOSSES 

forms the one and only criterion of the de- 
gree of economy or waste. 

Having obtained the efficiency of the plant, 
we shall immediately know whether its per- 
formance is above or below good practice. 
If it happens to be below (as is generally the 
case) it becomes necessary to study and to 
analyze the inefficiency and the waste. These 
are always the -differences between the care- 
fully determined percentage of efficiency and 
100 per cent. Thus we know exactly what 
part of the heat of the coal is converted into 
useful steam and what portion is lost or 
wasted. 

If we had to stop at this point in our de- 
terminations, our knowledge and consequent- 
ly our ability to improve would be limited. 
But owing once more to our natural laws of 
conservation, we are enabled to measure all 
of the losses as well as the percentage of heat 
utilized. This analysis of waste, together 
with the efficiency, must invariably total up 
to the original heat in the coal at the begin- 
ning of the operation. Such a balance of 
efficiency and loss is known as the "heat bal- 
ance." With the heat balance before us, we 
shall not only know where the greatest losses 
occur but we shall also know what causes 
them, and consequently how to reduce them. 
We are therefore able to work intelligently 



THE BOILER PLANT 57 

and can predict with great certainty the 
amonnt of saving that will, be produced by 
making the changes of operation or design 
that are correctly indicated by the charac- 
ter and extent of the established losses. 

The actual determination of the heat bal- 
ance involves in the first place a thorough 
and complete boiler test, together with a 
knowledge of chemistry, for combustion in- 
volves the conversion of chemical energy into 
heat energy. 

HEAT BALANCE OF A BOILER AND ITS FURNACE 

Total Heat Value of one pound of combustible — 
100 per cent 

Per cent 

Heat absorbed by the boiler — useful x 

Losses accounted for: 

Loss due to moisture in the coal a 

Loss due to moisture formed by burning of 

hydrogen b 

Loss due to heat carried away by dry chim- 
ney gases c 

Loss due to incomplete combustion of car- 
bon d 

Loss due to incomplete combustion of hy- 
drocarbons e 

Loss due to incomplete combustion of sul- 
phur f 

Loss due to moisture in the air and to radia- 
tion g 

Loss due to combustible dropping through 
grate and removed in cleaning fire, also 
heat so removed h 

Total of losses plus useful heat 100 



58 PREVENTING POWER-PLANT LOSSES 

It is aside from the purpose of this book 
to enter upon a detailed discussion of boiler 
testing, of combustion or of steam, for any 
one of which great volumes would be re- 
quired. It is simply desired to indicate those 
sources of knowledge upon which it is neces- 
sary to draw freely for the production of a 
complete and informative boiler test. Hav- 
ing done so in a brief manner let us examine 
the items which make up our heat balance, 
which has been the practical object of our 
test. 

In order to obtain the data from which to 
calculate our heat balance it is necessary to 
make an average day's run on the boiler or 
boilers and to take careful and accurate rec- 
ords of water, coal (including its weight, 
moisture, calorific value and chemical analy- 
sis), readings of all essential temperatures, 
pressures, and draft tests. With a proper 
testing equipment this is not so complicated 
and difficult as it may appear and, when it 
becomes understood that by such means alone 
can the preventable losses be determined, the 
application of this particular branch of prac- 
tical science will increase with even greater 
rapidity than has marked its progress in re- 
cent years. If we carry this out thoroughly, 
then when we have made our efficiency test, 
which may indicate a poor economy, the heat 



THE BOILER PLANT 59 

balance tells us exactly why our result was 
so poor. 

If then we add to our heat balance the fac- 
tor of commercial economy, involving a de- 
termination of the comparative values of all 
of the available fuels on the local market, 
we shall have covered the ground so com- 
pletely that we shall have definite knowledge 
of the correct solution of our problem. We 
shall know how many dollars per year can 
be saved, and how to go about producing 
that saving without guesswork as to any 
of the factors involved. 

In order to demonstrate the actual work- 
ing of the heat balance I will quote from 
a section of one of my reports on a small fac- 
tory boiler plant. The figures and notes fol- 
low: 



HEAT BALANCE BASED ON COMBUSTIBLE, A. S. M. E. 
CODE 

Combustible = 15,445 B.t.u. per lb. 

B.t.u. Per cent 

1— Heat absorbed by boiler 8, 155 52 . 80 

2 — Loss due to moisture in the coal 22 . 14 
3 — Loss due to moisture formed 
by burning to hydrogen (5 
per cent H assumed in com- 
bustible) 544 3.52 



60 • PREVENTING POWER-PLANT LOSSES 

B.t.u. Per cent 
Brought forward 8,721 56.46 

4 — Loss due to heat carried away 
in dry chimney gases (weight 
of gas per lb. combustible X 
0.24 X [T — t]) 3,700 24 

5 — Loss due to incomplete com- 
bustion of carbon (C to CO) . 

6 — Loss due to unconsumed hy- 
drogen and hydrocarbons, 
to heating moisture in air, to 
radiation, carbon in dis- 
charged ash and unaccount- 
ed for (by diff.) 3,024 19. 54 



TOTALS 15,445 100 . 00 

Notes on Heat Balance 

The loss due to heat carried away in dry chimney 
gases is shown in Item 4 in the above balance. This 
is computed according to principles laid down in 
Chapter XII on Combustion. From formulas in this 
Chapter it is determined that by improving the fir- 
ing so as to increase the C0 2 from 5.35 per cent to 
10 per cent, the dry chimney loss will be reduced 
from 24 per cent to 11.7 per cent of the heat of the 
combustible. That is to say, 12.3 per cent of the 
heat involved will be added to the old efficiency of 
52.8, making the new efficiency 65.1 per cent. The 
saving in coal for the same amount of steam produc- 

12 3 

tion will be — V = 19 per cent while the gain in 
oo.l 

steam for the same coal consumption as at present 

12.3 
will be — ^— =23.3 per cent. 

O^5.o 

The method of the above determinations was as 
follows. From the composition of the fuel, the chem- 
ical air requirements were obtained with the formula 



THE BOILER PLANT 61 

A = 11.6 + (34.8 X H a ). The corresponding or 
maximum C0 2 was obtained from the formula P = 

— — _,,. TT . The weight of the dry products of 

152 + ool il a 

combustion was found for 5.35 C0 2 and 10— CO2 by 

means of the formula W d = 11.6 + 1 + A e + 0.77 

(H a X 34.8) in which H a - H - — and for which 

o 

A e is obtained by solving for it in the formula P = 

11.6 X 21 
11.6 + 26.7 H a + A e * 

With W d known for the two conditions of analysis, 
the dry gas chimney loss is computed for each case 
and the reduction of this loss by the increase of CO2 
is directly added to the old efficiency. 

Simply improving the combustion would create 
this gain, but there would also be an attendant gain 
from reduction of .radiation losses by firing a single 
boiler instead of two boilers. Consequently the 
above saving is a safe figure, especially as no fancy 
efficiency is called for. 

As a check upon these figures a 23.2 per cent gain 
in evaporation over the present evaporation of 7.3 
would give 9 pounds of water per pound of coal from 
and at 212 degrees. 

This evaporation of 9 pounds would represent a 
combined efficiency of 9 X 970.4 -f- 13,400 = 65 
per cent efficiency. 

To give this result in terms of actual evaporation 
under observed conditions with the city water tem- 
perature as tested, the above result would correspond 
to 9 4- 1.18 = 7.62 pounds instead of the evaporation 
found in test amounting to 6.09 pounds. 

The change in the method of firing as spec- 
ified was put into immediate effect, and the 
results obtained exceeded the safe predic- 
tion that the heat balance made possible. The 



62 PREVENTING POWER-PLANT LOSSES 

actual saving was over 25 per cent of the 
coal formerly consumed. 

So much for thermal efficiency pure and 
simple. The commercial efficiency of the case 
was then calculated and I again quote from 
my report in this regard. 

Anthracite screenings in this particular locality, 
however, seem to offer a much more attractive solu- 
tion of the problem. 

Good screenings or D & H birdseye contain 11,000 
to 12,000 B.t.u. per pound, as compared to 13,400 
B.t.u. in your present $3.50 soft coal. 

The delivered prices on the former according to 
your information run from $0.90 to $1.40 per ton. 
The sample given me of the $1.40 coal from the X. Y. 
Coal Co. appears to be a very high grade of this fuel 
which, however, will vary more or' less. 
. Now in order to make the following calculation a 
safe one I will figure on $1.40 instead of $0.90 per 
short ton, and on only 11,000 B.t.u. per pound. 

Thus we have the following comparison with your 
present coal, moisture content assumed to be the 
same in each coal. 

Table of Coal Value Comparisons 
Present coal, bituminous $3.50 per 2,000 pounds 

delivered, 13,400 B.t.u. per dry pound. 
Anthracite screenings, $1.40 per 2,000 pounds de- 
livered, 11,000 B.t.u. per dry pound. 

Cost of 1,000,000 Heat Units (B.t.u.) 
Present coal, bituminous 

a 2,000 X 13,400 B.t.u. = $ai3 ° 5 
Anthracite screenings . 

2,000 X 11,000 B.t.u. = l0 -° 637 

Based on a safe heat value and the highest price 



THE BOILER PLANT 63 

per ton, the same amount of heat would cost you 
$0,064 with the screenings as compared to $0.1305 
with the present soft coal. 

Consequently if you burned the anthracite screen- 
ings at the same low efficiency now found to be ob- 
taining with the soft coal, your coal bill would be 
0.0637 -r- 0.1305 = 48.8 per cent of present bill, or 
a saving of 51.2 per cent per year of the present 
expense. 

This figure, however, 51 per cent, does not repre- 
sent the full saving that you can obtain by a sub- 
stitution of this fuel, for the reason that instead of 
burning same at your present efficiency you would 
be able easily to burn it at an efficiency of 65 per 
cent with a properly designed equipment. I have 
designed two plants for this fuel which are operating 
at an even higher efficiency than this. 

Your cost of evaporation with 11,000 B.t.u. 
screenings at $1.40 per 2,000 pounds delivered, at 
65 per cent efficiency, would be (at the rate of 7.37 
pounds evaporation from and at 212 degrees) 
1,000 $1.40 
T37 X 2^00 = $ °- 095 
per 1,000 pounds of steam from and at 212 degrees. 

As a further comparison and check upon these 
statements, one of my plants has a cost of evapora- 
tion of $0.10. 

Your present cost of evaporation is $0,244. Con- 
sequently by taking the proper steps you have a coal 
cost saving waiting for you amounting to (0.244 — 
0.10) -f- 0.244 = 59 per cent of your present yearly 
coal bill. That is to say, about 60 per cent of the 
coal bill can be saved on a conservative estimate. 

It will be remembered that this estimate is figured 
on 11,000 B.t.u. instead of 12,000 B.t.u.- coal, and 
on a price for same of $1.40 instead of a possible 
$0.90. 

Since the original writing of this section 



64: PREVENTING POWER-PLANT LOSSES 

all these changes have been carried out and 
have now been in operation abont a year. 

The client now reports his average cost of 
evaporation at about 9 cents instead of 
his original fuel cost of 24.4 cents. That is, 
his saving by these changes amounts to 63 
per cent of his former coal bill. 

Thus we have an example from an actual 
case of the application to the boiler plant 
of the method of investigation logically 
evolved by, and dependent upon, the laws of 
the conservation of energy. We have in- 
troduced the money factor in its relation to 
thermal value, with the result of discovering 
a saving of over 60 per cent of the original 
coal bill. 

It is the duty of the investigating engineer 
to translate into physical and financial terms 
the items of the heat balance, the determina- 
tion of which forms the first part of his task. 
These items of wasted heat are directly trace- 
able to certain causes which vary in number 
and kind as the case may develop, but in 
order to obtain a working idea of how this 
translation is effected let us take our heat 
balance and run over a brief description both 
of the determination and of some of the prac- 
tical means of eliminating or reducing these 
losses. 

We have already discussed, with sufficient 



THE BOILER PLANT 65 

amplification for our purposes, the method of 
calculating the efficiency or useful percentage 
of the heat in the coal as determined from 
part of the data observed in the boiler test. 
We shall now consider each item of loss in 
turn, using the simplest form of heat bal- 
ance based on combustible, and for this pur- 
pose (which is simply for illustration) we 
shall follow the form of the heat balance last 
quoted. 

The heat value of the coal in this case was 
13,400 B.t.u. per pound, dry. The ash in 
this coal by analysis was 13.24 per cent. 
Consequently the combustible matter was 
only 86.76 per cent and its heat value per 
pound must therefore be 13,400 B.t.u. -f- 
0.8676 or 15.445 B.t.u. 

The first heat loss is that due to moisture 
in the coal and is numbered "2" in the bal- 
ance. This water has to be raised from the 
temperature of the air in the fireroom to the 
temperature of the hot gases leaving the boil- 
ers, and in so doing is converted into super- 
heated steam, thus involving the large item 
of its latent heat, i. e., 970.4 B.t.u. per pound. 
In addition, sufficient heat must be added to 
each pound of water to raise its temperature 
from that of the fireroom air up to 212 de- 
grees, and again from this point in the form 
of steam gas up to the chimney tempera- 



66 PREVENTING PO WEE-PLANT LOSSES 

ture. All of these factors are taken as part 
of the boiler-test observations, so the loss 
is readily calculated. In this case it amount- 
ed to only 22 heat units for each pound of 
combustible or 0.14 per cent of the heat to 
the furnace. 

The second loss is due to moisture formed 
by the burning of hydrogen to water or steam 
gas, and the heat carried away by each pound 
of such steam is calculated in the same way 
as just described for the moisture in the coal. 
It is first necessary, of course, to determine 
how much of this steam is formed per pound 
of combustible fed to the furnace. This is 
obtained by taking the percentage of hydro- 
gen in the fuel and performing a simple 
chemical calculation. In this case our hydro- 
gen moisture loss amounted to 3.52 per cent 
of the heat of the combustible. 

The next or third loss is the amount of 
heat that is carried away up the chimney by 
the dry hot gases of combustion. This is com- 
monly called the chimney loss, and is of the 
utmost importance in boiler practice. Its cal- 
culation depends upon the temperature and 
the weight of these gases as they leave the 
boiler. Here again we must resort to chem- 
istry, and during our test we have taken a< 
large number of samples of the flue gases and 
have subjected them to analysis in a chemi- 



THE BOILER PLANT 67 

cal apparatus which determines the volumet- 
ric proportions of C0 2 (carbonic acid gas, 
the product of complete combustion of car- 
bon), (free oxygen that has remained un- 
combined or has played no part in the com- 
bustion), CO (carbon monoxide, or half- 
burned carbon) and nitrogen, the inert 
portion of the atmosphere which acts merely 
as an unavoidable diluent and cooling agent 
of our combustion gases. From these data 
we are able to determine the amount or 
weight of air that has been supplied per 
pound of combustible, and consequently the 
weight of the resulting products of combus- 
tion. This chimney-loss computation in- 
cludes leakage of air through the boiler set- 
tings. Chemistry and physics give us the 
specific heat of these various gases, and 
knowing their temperature and their weight, 
these three factors are multiplied together 
and the resulting product is the number of 
heat units in the dry chimney gases for each 
pound of combustible supplied to the furnace. 
In this particular case the chimney loss 
amounted to 3,700 B.t.u., or 24 per cent of 
the heat of the combustible. The chemical 
analyses made during the test also showed 
that about 43 pounds of air were being sup- 
plied to the furnace for each pound of com- 
bustible, whereas in good practice only 18 



68 PREVENTING TOWER-PLANT LOSSES 

pounds are required. This great amount of 
surplus air beyond the combustion require- 
ments was absorbing heat from the coal and 
carrying it away up the chimney, instead of 
allowing it to be absorbed by the boiler. 
Hence it was plainly indicated that this air 
supply should be reduced. Now other data 
from our boiler tests showed a very low rate 
of consumption of coal to the square foot of 
grate surface. That is, the grate was too 
large for the amount of coal to be burned, 
and consequently admitted too much air to 
the fire. Here, then, was the cause of the 
large chimney loss, with plain indications of 
what the cure should be. This cure was put 
into effect by reducing the grate surface 
more than 50 per cent and improving the fir- 
ing, with the result that the air supply was 
reduced to less than one-half and the weight 
of the dry chimney gases was reduced from 
43.8 pounds per pound of combustible to 21.5 
pounds. The new chimney loss would then 
become 21.5 -=- 43.8 of 24 per cent or 11.7 per 
cent, representing a gain of 12.3 per cent to 
be added to the old efficiency of 52.8, making 
the new efficiency 65.1 per cent. The saving 
in coal would then be (65.1 — 52.8)-^ 65.1 = 
about 19 per cent. As a matter of fact, the 
effect was greater than this prediction which 
was on the "safe side" and the true saving 



THE BdlLEK PLANT 69 

was over 25 per cent of the coal originally 
consumed for the same output of steam. 

This case of too great an air supply is a 
very common one. Most people think that 
good combustion is simply a matter of am- 
ple air supply. As a matter of fact, more 
waste of coal is likely to occur from an over 
supply than from too little air. 

In this particular case I have quoted more 
smoke was produced after the combustion 
was improved than before. This demon- 
strates what is so poorly understood, that 
smoke may indicate less waste than no smoke. 
A smokeless chimney may be produced by 
flooding the fire with air, but this entails a 
heavy increase in the chimney loss with a 
consequent waste of coal. This does not mean 
that it pays to make smoke, although for a 
given furnace and set of conditions it may 
be so. In other words, there are cases when 
the losses due to incomplete combustion as 
indicated by smoke may be less than the 
losses due to the admission of sufficient air 
to "kill" the smoke. This is the weak point 
of many so-called ' ' smoke-consumers ' '. The 
science of the matter lies in the production 
of perfect combustion, which is necessarily 
smokeless and which at the same time in- 
volves a correct proportioning (neither an 
excess nor a deficiency) of air to the fuel. 



70 PREVENTING POWER-PLANT LOSSES 

The production of such combustion is not 
entirely controlled by the simple matter of 
air admission, but to as great an extent by 
the intelligent design of the furnace itself. 
This involves the maintenance of high tem- 
perature and the thorough mixing of the air 
with the combustion gases and with the car- 
bon, and constitutes a science in itself. 

The fourth loss imour heat, balance (item 
No. 5) is occasionally by the incomplete com- 
bustion of the carbon of the coal. When 
carbon burns completely it forms C0 2 , which 
is carbonic-acid gas or carbon-dioxide, and 
the heat generated by this union with oxygen 
is 14,600 B.t.u. for each pound of carbon so 
burned. When carbon burns incompletely it 
forms CO, or carbon monoxide, which upon 
addition of more oxygen burns to C0 2 . But 
since the burning of carbon to CO develops 
only 4,450 B.t.u. for each pound of carbon so 
burned we have lost (14,600 — 4,450) =10,- 
150 B.t.u. 

Now from the analyses of the chimney 
gases made during our boiler test, we can 
compute how much of the carbon of our com- 
bustible has been incompletely burned to CO 
and consequently how much heat has been 
lost by this cause. In this special case with 
the great excess of air present the loss from 
this source was nil. In some boiler tests, 



THE BOILER PLANT 71 

however, a large loss is indicated. It may 
be due to insufficient air supply, and if this 
is the case it will be so indicated by the very 
small excess of free oxygen as shown by the 
flue-gas analyses. If sufficient oxygen is pres- 
ent, then the loss is chargeable either to lack 
of thorough mixing of the air with the fuel 
and combustion gases, or to low temperature 
in the fire. These effects are traceable di- 
rectly to furnace design and the method of 
firing, and when thus investigated can be 
corrected to the direct improvement of our 
efficiency as would be indicated by this item 
in the heat balance. 

The next loss to be considered forms a 
part of item No. 6 and is that due to the di- 
rect removal of combustible matter. This is 
caused first by unburned fuel dropping 
through the grate into the ashpit. The loss 
thus occasioned is determined by analyzing 
the ash for its carbon content. Its weight 
multiplied by its heat value equals the loss. 
Another item of this waste occurs when in- 
candescent clinker is removed from the grate 
during cleaning operations. In addition- to 
the unconsumed carbon in this hot substance, 
a certain amount of heat is contained in the 
heated mass, which can be computed by 
means of its temperature, weight and spe- 
cific heat. 



72 PREVENTING POWER-PLANT LOSSES 

In further sub-division of our last item 
there is the loss due to heating the moisture 
in the air. This is so -small that in commer- 
cial work it may be neglected. The waste due 
to unburned hydrogen and hydrocarbons 
from the coal may be a large percentage, de- 
pending principally upon the volatile constit- 
uent of the fuel and how it is handled. This 
loss together with that due to radiation is 
generally found by deducting all the other 
items from 100 per cent, this being the sim- 
plest and most direct solution. 

As hard, or anthracite, coals contain very 
small percentages of volatile matter, the loss 
due to escaping hydrocarbons is naturally 
small. But certain soft coals contain as much 
as 40 per cent of volatile material consisting 
largely of marsh gas (CH 4 ) which has a high 
heat value. When a shovelful of such soft 
coal is thrown into a hot furnace the greater 
part of this percentage of volatile matter at 
once becomes freed from the coal, and the 
generation of this valuable fuel gas is so 
rapid that unless the furnace conditions are 
right for its combustion most of it passes 
out of the boiler and up the chimney as a 
dead loss. This action is generally accom- 
panied by smoke, which consists of uncon- 
sumed particles of visible carbon and tarry 
matter escaping with the invisible but valu- 



THE BOILER PLANT 73 

able fuel gases. The smoke itself is an in- 
significant loss compared with the gases 
which frequently accompany it. The study of 
this loss teaches us to fire our coal a little 
at a time, so that there will be sufficient heat 
and temperature in the surrounding parts 
of the furnace to cause its ignition and 
enough air to permit its complete combus- 
tion. This results directly in reducing the 
smoke and the hydrocarbon loss at the same 
time, which brings us again to the matter of 
furnace design and operation. Waste of fuel 
may be caused by unintelligent handling of 
fires in a very good furnace, while good firing 
will not give best results in a bad furnace. 
Thus with the much contracted combustion 
space found in many settings it will be very 
difficult for the best fireman to get high ef- 
ficiency, especially under forced conditions, 
while a scientifically designed furnace is no 
guarantee of good combustion unless intel- 
ligently handled. 

While we shall not be allowed to under- 
take a discussion of the absorbing subject 
of furnace design, it will at this time be apro- 
pos to state a condition which vitally affects 
the loss due to unburned hydrocarbons from 
soft coals, for it is desired to learn in some 
measure what are some of the common meth- 
ods of reducing the losses which have been 



74 PREVENTING POWER-PLANT LOSSES 

located and measured in our heat balance. 
Aside from the loss due to excessive air 
supply as evidenced in the "chimney loss" 
item, the greatest waste in the burning of 
soft coal appears in the escape of a large 
percentage of its volatile constituent imme- 
diately following the introduction of the coal 
to the furnace or the slicing of the fire. 
Either operation liberates large volumes of 
the hydrocarbon gases, which ordinarily flow 
out of the furnace with great rapidity under 
the influence of the draft. The time element 
is of the utmost importance, for if these gases 
could be held in the furnace a sufficient length 
of time for thorough heating and diffusion 
with the oxygen, the greater portion of them 
would undergo combustion with a consequent 
development of the heat otherwise wasted. 
One of the very simple and effective means 
employed to accomplish this result is to pro- 
vide large draft areas over the fire and in 
the combustion chamber. With a given flow 
of gases and air their velocity will be in- 
versely proportional to the cross-section of 
the passage. Thus these volatile constituents 
can be retained in hot combustion spaces for 
double the time they formerly spent. Lower- 
ing the grate to bring the fire farther away 
from the boiler and deepening the combus- 
tion chamber often produces the desired re- 



THE BOILER PLANT 75 

suit, which may be further benefited by the 
intelligent design of proper brick arches or 
baffle walls to aid the mixing action before 
referred to. 

A great deal of misunderstanding exists 
in regard to the effect of placing the grate 
further away from the boiler. It is common 
belief that the nearer the fire is to the boiler 
the greater will be the resulting efficiency. 
But the very opposite is true within reason- 
able limits, especially with soft coal, and 
even with anthracite it is advantageous to 
have the grate much lower than is found in 
general use. The trouble is that people do 
not distinguish between the diametrically op- 
posed functions of the boiler and furnace. 
The duty of the furnace is to produce com- 
plete combustion of the fuel, and for this 
purpose it must develop a maximum of heat 
at a maximum temperature. The boiler on 
the other hand is essentially a heat absorber, 
and to be efficient must reduce the tempera- 
ture and the heat developed by the furnace 
to a minimum. Consequently the boiler if 
placed directly in the flames of the furnace 
reduces the temperature and retards the com- 
bustion by cooling the gases below their igni- 
tion point, which allows them to escape un- 
burned. It follows that the two functions 
of furnace and boiler must be sufficiently 



76 PREVENTING PO WEE-PLANT LOSSES 

separated to allow complete combustion and 
full development of the heat from the fuel 
before the severe cooling effect of the boiler 
takes place. 

At this point we logically come to the next 
item of heat losses : i. e., radiation. In a brick- 
set externally fired boiler this loss may 
amount to from 3 to 5 per cent of the heat 
of the combustible and in certain unusual 
cases considerably more. It may be reduced 
by covering the' boiler setting with an ample 
thickness of asbestos or other heat insulating 
material. 

It may be further reduced by employing 
boilers of the internally fired variety, that 
is boilers whose furnaces are surrounded by 
water-heating surfaces, like the Scotch ma- 
rine, the locomotive and Manning upright 
types. The loss due to radiation is of course 
much reduced in these boilers. But some- 
times the lack of hot brickwork and insuffi- 
cient combustion space results in such incom- 
plete combustion, especially under forced 
conditions with soft coal, that the slight in- 
crease of efficiency by reduced radiation is 
more than offset by the loss occasioned by 
unburned fuel gases forced into contact with 
the cold boiler surfaces before their ignition 
and combustion can take place. In one test 
of this kind upon an internally fired boiler 



THE BOILEK PLANT 77 

I found at times enough unburned gas in the 
chimney to run a gas engine. It does not 
pay to go very far to reduce radiation by 
internal firing, especially when soft coal is 
burned. The advantages of the internally 
fired boilers are principally governed by local 
conditions such as limited floor space and 
absence of brickwork which will reduce up- 
keep expense. 

The item of radiation may be roughly com- 
puted in the case of internally fired boilers 
by means of the area exposed, or covered 
with a material whose heat flow is known, to- 
gether with the temperature of the steam 
and surrounding air. For brick-set boilers 
it may be obtained by subtraction of the 
other losses, but in most instances is of 
insufficient moment to demand the expendi- 
ture of great effort in its accurate determina- 
tion. 

We have now reviewed, one at a time, all 
the essential losses which constitute the en- 
tire waste connected with the operation of 
a steam boiler, and we have also had a prac- 
tical example of the application of such an 
analysis to a factory boiler plant. In that 
particular instance an immediate saving of 
25 per cent of the coal was the direct result. 
And when financial factors were combined 
with the thermal a means was discovered for 



78 PREVENTING POWER-PLANT LOSSES 

again reducing the fuel cost about 50 per cent 
more. 

Thus we have an idea of the theory and 
practice of scientific investigation as applied 
to the boiler plant. 



Chapter IV 
THE BOILER PLANT (Continued) 

A GREAT many questions arise in every 
■**■ plant regarding the economy of this 
or that contemplated change in operation or 
equipment. If such considerations were 
properly regarded at the beginning, before 
the plant was designed, there would not be 
the present large number of factory boiler 
plants that are operating with a large pre- 
ventable waste. 

In one plant for instance I found excellent 
boilers and a good type of stoker furnace, but 
poor efficiency. Here the trouble was due to 
lack of investigation beforehand. The boil- 
ers were not balanced to the load conditions 
and the furnaces were too big for the boilers. 
A boiler could not be taken off for cleaning 
without running the other much beyond 
its economic rating, which caused a great 
chimney loss. If both boilers were operated, 
the furnaces were so large for this appor- 
79 



80 PREVENTING POWER-PLANT LOSSES 

tionment of load that they had three times 
as much grate surface as should have been 
provided for this condition, and this resulted 
also in a heavy loss of fuel. This was a diffi- 
cult case to improve, since the great mistake 
had been made of buying equipment out of 
proportion to the work to be done. One of 
the first considerations in the design of a 
plant is the question of the number and size 
of the boilers to be specified. In deciding this 
matter three special requirements must be 
met. 

1.— Extra boiler for cleaning. 

2. — Efficiency at different factory loads. 

3. — Growth of plant. 

The efficiency of a boiler at different rates 
of driving is of primary importance in the 
above determinations, and before discussing 
them further it will be of advantage to un- 
derstand what is meant by the "rating" of 
a boiler, and what factors influence its horse 
power or capacity. The mistake is frequent- 
ly made of basing the purchase of a boiler 
on a simple horse-power rating. That this 
practice is most unsafe and results in much 
trouble will be quickly realized when I state 
that boiler manufacturers differently define 
a rated horse power as related to heating sur- 
face. There is, however, an accepted stand- 
ard, that of the American Society of Mechan- 



THE BOILER PLANT 81 

ical Engineers, which states that a boiler 
horse power shall be considered the evapo- 
ration of 34.5 pounds of water per hour into 
steam from and at 212 degrees. This is 
equivalent to the evaporation of 30 pounds 
of water from a feed-water temperature of 
100 degrees into steam at 70-pounds pres- 
sure, and is roughly the amount of steam 
required to produce a horse-power hour with 
a simple Corliss engine at this pressure and 
non-condensing. Thirty pounds of water per 
hour is therefore a boiler horse power. 

Now the voluminous data on boiler testing 
in the past have indicated that an ordinary 
boiler operates at its best efficiency when 2y 2 
to 3 pounds of water per hour are evaporated 
for each square foot of its heating surface 1 . 
At these rates the development of a horse 
power would require 

30 30 

^— — or -77-= 12 or 10 square feet 

ZJ/2 O 

of heating surface respectively. Conse- 
quently a 100-horsepower boiler should con- 
tain 1,200 or at least 1,000 square feet of heat- 
ing surface. But 30 pounds of water per 
hour can be evaporated with as little as 5 
square feet, whereas it was comparatively 
recent practice to allow 15. Here, then, is a 

1 Heating surface — That portion of the metal in a boiler which has 
water on one surface and fire or hot gases on the other. 



82 PREVENTING POWER-PLANT LOSSES 

range of 300 per cent in the factor determin- 
ing how much heating surface makes a boiler 
horse power. 

Consequently a boiler containing 1,000 
square feet may be rated at 100 horse power 
at 10 square feet, or 200 horse power at 5 
square feet, or only 66 horse power at 15 
square feet of heating surface per horse 
power; so if these factors are not stated a 
rated boiler horse power means nothing. 

I had a case where the plant owners had 
believed that horse power was horse pow r er, 
and that was all there was to it. They pur- 
chased two boilers guaranteed to give an 
overload of 50 per cent. As there was no 
specification regarding the amount of heat- 
ing surface, the manufacturer supplied only 
7% square feet per horse power instead of 
10 or 12 square feet, which should have been 
called for in proper specifications. Now 
when the boilers were installed and operated 
under the guaranteed overload of 50 per 
cent, a horse power had to be developed with 
5 square feet of heating surface. The result 
was that the boilers were actually run at 100 
per cent over their normal rating, and their 
thermal efficiency was so low and the coal bill 
so high that it was necessary to call in expert 
advice, all of which might have been avoided 
if the plant owners had in the first place 



THE BOILER PLANT 83 

taken steps to learn what a boiler horse 
power meant before attempting to use the 
term in the equipment of their plant. 

The amount of heating surface that can 
economically develop a boiler horse power 
is at the present time a subject of close study 
and experiment and depends upon a knowl- 
edge of the laws of heat transference. With 
present-day equipment it is wise to provide 
at least 10 square feet of heating surface, 
although we may look for a considerable 
reduction of this figure in future practice. 
In any event, the capacity of a boiler will 
always be proportional to its heating surface 
and a purchaser who does not demand a full 
allowance is cutting himself off from a part 
of the capacity and efficiency to which he is 
entitled. 

In a boiler test it is always important to 
determine at what per cent of their true 
rating the boilers are being driven, as this 
seriously affects their economy. Their true 
rated capacity is first obtained from a meas- 
urement of their heating surface in square 
feet, which divided by 10 results in rated 
horse power. Then if a boiler plant is found 
to be operating at considerably less than its 
rated capacity, and if the furnaces are cor- 
rectly proportioned to the boilers, it is alto- 
gether likely that a large "chimney loss" 



84 PREVENTING POWER-PLANT LOSSES 

will be found. For this condition would in- 
dicate that the grate surface is too large for 
the rate of coal consumption, and consequent- 
ly a surplus of air supply to the fires may 
be expected. This is simply stated by assum- 
ing that under a given set of conditions a 
square foot of grate will supply enough air 
for the proper combustion of 20 pounds of 
coal per hour. Then if only 10 pounds are 
burned, the grate may supply double the 
amount of air required for combustion, with 
the attendant waste described under "chim- 
ney loss". 

Having now touched upon the meaning of 
capacity, we can refer with better under- 
standing to the matter of fixing correctly the 
number and size of boilers adapted to best 
efficiency under any given set of local condi- 
tions. Perhaps the clearest way to indicate 
the method of determination of this matter 
will be to quote from one of my reports the 
portion bearing directly on this question, con- 
nected with the particular requirements which 
are stated or implied. While this plant was a 
small one the treatment illustrated governs 
all cases. 

The first consideration in the design of any plant 
is the load to be carried. In the summer time as 
per test made on boilers this average summer load 
was found to be 162 boiler horse power. Allowance 



THE BOILER PLANT 85 

should be made for an increase in the use of steam in 
the winter time owing to an additional load of about 
300 amperes as compared to 800 in the summer time. 
This makes an increase of 37.5 per cent, so that the 
maximum average load for winter at present may be 
calculated at 223 boiler horse power. 

Consequently the boiler plant should be able to 
handle 162 horse power to 223 horse power econom- 
ically, and also allow for cleaning a boiler when neces- 
sary, and in addition to these requirements must be 
so designed as to provide for an increase in power re- 
quirements with a growth of the business. 

Now if one extra boiler be provided for cleaning 
purposes, you can have either two boilers or three 
boilers. 

If two boilers are selected, then one boiler alone 
must carry at good efficiency a load ranging from 
162 to 223 horse power, and allowing 50 per cent for 
growth of plant it should also be able to handle 335 
horse power. This is too high a load for a high- 
pressure horizontal tubular boiler unless it is of 
special design. 

If three boilers are specified, then two of these 
boilers must carry 162 to 335 horse power. If they 
are each 150 horse power normal rating then one 
boiler will handle the 162 horse-power load very effi- 
ciently, and two boilers will handle the 335 horse- 
power load with equal efficiency, which includes the 
allowance for 50 per cent growth over present maxi- 
mum-load requirements. 

The intermediate maximum winter load of 223 
horse power could be handled by one boiler at 148 
per cent of its normal rating, or by two boilers at 
74 per cent of their combined rating. 

Three boilers therefore make the best number 
for economical running under these various load re- 
quirements, and would take care of the following 
specifications: 

1 — Extra boiler for cleaning 



86 PREVENTING POWEK-PLANT LOSSES 

2 — Economy at different loads 

3 — Growth of plant. 

Now if the power requirements should increase 
from the present maximum winter load of 223 horse 
power to 446 horse power, this proposed plant of 
three 150 horse-power boilers would handle the load 
(which includes a 100 per cent increase of power) 
very efficiently with all three boilers running. If 
one boiler were taken off for cleaning it would mean 
taking 446 horse power out of two 150 horse-power 
boilers, or running two boilers for a day at 148 per 
cent of their capacity. This could be done very 
easily with fairly good efficiency. 

Therefore three 150 horse-power boilers would 
really provide for 100 per cent increase over the 
present maximum power requirements, and would 
make a plant adapted to handle all loads between 
the present light summer load and a possible future 
load of twice the present maximum requirements, 
and all loads in between, at high efficiency. 

Each boiler should have 1,800 square feet of heat- 
ing surface, that is 12 square feet per horse power. 

Very efficient operation is possible at re- 
duced capacities. I have obtained over 71 
per cent efficiency on a 200 horse-power 
boiler (rated at 12 square feet per horse 
power) when it was developing slightly over 
100 horse power. In this case the grate was 
very small, which permitted a normal rate 
of combustion without an excessive air sup- 
ply, and the high efficiency was also attrib- 
utable to a specially controlled furnace and 
draft. 

If a boiler is forced beyond its best normal 



THE BOILER PLANT 87 

rating it is not able efficiently to absorb the 
large amount of heat developed by the com- 
bustion of the fuel. Consequently this sur- 
plus heat passes the boiler and appears as 
additional chimney loss. 

With an allowance of 12 square feet of 
heating surface per horse power, a boiler 
with a well designed furnace may be driven 
with good efficiency at 50 per cent above its 
normal rating. This corresponds to 8 square 
feet of heating surface per boiler horse 
powder developed. In some cases it may pay 
to increase this amount of forcing to double 
the rated horse power. This is done for in- 
stance to meet peak loads in the 59th street 
Interborough Station, New York City, where 
cost of space and investment for additional 
boilers would be more expensive than the 
loss of efficiency occasioned during the few 
hours per day that this measure is necessary. 
This would seldom if ever be advisable, how- 
ever, in a factory power plant. For the usual 
factory imposes a comparatively steady load 
on the boilers, so that their number and size 
may be specified to give efficient operation, 
providing the load requirements are studied 
in advance. 

A question often involved in factory power 
investigations relates to the comparative fuel 
economy of fire-tube versus water-tube boil- 



»5 PREVENTING POWER-PLANT LOSSES 

ers. I have found that there is a general 
feeling that water-tube boilers are inherently 
more efficient than the fire-tube type. But 
this is not true. The brick setting of the 
water-tube boiler presents the greater ra- 
diating surface and consequently it is at a 
slight disadvantage in this respect. Other- 
wise there is no intrinsic reason why better 
economy of fuel should be expected with one 
kind than the other, providing of course the 
furnace is equally well designed in either 
case. 

The real factors governing the selection 
of type are — steam pressure, load curve, fa- 
cility of cleaning, first cost, and sometimes 
floor space in the case of large units. 

With a comparatively steady load such as 
obtains in most industrial plants, and with 
an engine plant which does not demand a 
steam pressure above 140 pounds, the hori- 
zontal tubular boiler would show a marked 
advantage over the water-tube class provid- 
ing the plant were not of such large capacity 
as to require too great a number of the fire- 
tube boilers. This advantage would be ap- 
parent in greater facility of cleaning, lower 
first cost, and settings generally better adapt- 
ed to the combustion of soft coal. If the load 
to be carried is subject to severe fluctuations 
and sudden heavy demands for steam, the 



THE BOILER PLANT 89 

water-tube boiler must be specified since it 
contains less water and consequently is more 
quickly responsive to forcing of the fires for 
sudden and rapid steaming. That is why this 
type is almost invariably chosen for public- 
service plants where the load with its tre- 
mendous " peaks " demands an immediate re- 
sponse from the boilers. Then again in this 
service, where production of cheap power 
is the sole object without the opportunity 
to cheapen it still further by the utilization 
of exhaust steam, only high-pressure engines 
and turbines are employed. This require- 
ment necessitates the specification of water- 
tube boilers since the other type as a matter 
of design and strength is not adapted to high 
pressures. Then, as before implied, where 
large units are advisable the water-tube has 
the advantage, for the reason that the safe 
pressure of a tube or cylinder is inversely 
proportional to its diameter. Therefore 
when the size of a fire-tube boiler has reached 
a definite point, it becomes impracticable to 
develop larger units without disproportion- 
ate expense unless it is desired to meet very 
special conditions. An internally fired tubu- 
lar boiler of the Scotch type, where the prod- 
ucts of combustion do not come in contact 
with the shell, may however be made in larger 
sizes than the horizontal fire-tube type, and 



90 PREVENTING POWER-PLANT LOSSES ' 

will therefore frequently compete with water- 
tube boilers as largely evidenced in marine 
practice. 

The cost of evaporation is an incidental 
though useful determination in plant investi- 
gations. This is commonly expressed in 
"cost of fuel for evaporating 1,000 pounds 
of steam from and at 212 degrees". It is 
obtained directly from the observations of 
our boiler test, and is most useful as a figure 
of commercial comparison of one plant with 
another. Depending upon the fuel used and 
the location and efficiency of the plant, this 
item will vary between 10 cents and 28 cents 
in this country. Its use facilitates the deter- 
mination of the total cost of power and heat- 
ing when combined with the other essential 
factors involved in that result. Given a fixed 
price and heat value of coal, the cost of 
evaporation will be inversely proportional to 
the combined boiler and furnace efficiency, 
and in a plant where the above values are 
known to be constant this term can profitably 
be used as an accurate measure of gain or 
loss in its operation. 

A consideration of the condition of the 
feed water, both as to its temperature and 
as to its scale-forming properties, is essential 
to a complete investigation. It is needless 
to state that the accumulation of scale on 



THE BOILER PLANT 91 

boiler heating surfaces resists the transfer 
of heat and therefore acts to reduce the effi- 
ciency of steam production. Also, owing to 
this resistance to heat now, the boiler metal 
between it and the fire, being unable to trans- 
fer its heat to the water, will retain it and 
consequently become so hot as to cause bag- 
ging or blistering of the iron, resulting in a 
serious and sometimes dangerous injury to 
the boiler. The consumption of additional 
fuel due to scale is manifested in the produc- 
tion of an abnormally high chimney loss. 
Various figures are available which claim to 
show what percentage of the coal is wasted 
because of different thicknesses of scale, but 
I do not know of any truly reliable data of 
this description. It is also likely that dif- 
ferent kinds of scale have different heat-re- 
sisting properties, which consideration is 
generally disregarded. Furthermore, unless 
comparative tests, made for the determina- 
tion of such information, were in each case 
conducted with combustion of exactly the 
same quality and with a consumption of the 
same amount of coal, the resulting efficiencies 
would in no wise indicate the effect produced 
solely by the scale. It would also be difficult 
to find a boiler evenly coated with scale of 
anywhere near uniform thickness through- 
out. At present, therefore, it is sufficient 



92 PREVENTING POWER-PLANT LOSSES 

to desire to eliminate scale, as much from 
the standpoint of safety as for reasons of 
fuel economy, though both are important. 
Water contains two kinds of scale-forming 
"hardness": temporary and permanent. 
The temporary hardness consists principally 
of the carbonates of lime and magnesia and 
can be largely eliminated by raising the wa- 
ter to a temperature of about 190 degrees 
in an open vessel to allow the escape of car- 
bonic-acid gas. An open type of feed-water 
heater w T ith ample depositing and filtering 
arrangements is often the simplest solution. 
For neutralization of the permanent hard- 
ness, implying the presence of sulphates in 
the water, it is usual to resort to chemical 
purification. Special apparatus are available 
which are capable of combining the two oper- 
ations for both kinds of hardness. Perma- 
nent hardness may also be reduced by dupli- 
cating a part of the action of the boiler itself, 
by the use of a closed purifier in which the 
feed water is subjected to a high tempera- 
ture under pressure. These are questions 
involving chemical determination together 
with the best advice obtainable. 

Referring now to the consideration of the 
temperature of the feed water, we are able 
to measure exactly what effect this will pro- 
duce on our consumption of fuel. In the first 



THE BOILER PLANT 93 

place, let it be clearly understood that the 
temperature of the water that goes to the 
boilers has practically no effect upon their 
efficiency in spite of the fact that we shall 
save money by previous heating of this water. 
Now if we recall our definition of efficiency 
it will be simple to understand this apparent 
paradox. Efficiency == Output -r- Input. The 
output is the heat in the steam above the 
feed temperature. Since the boilers have no 
part in raising the water to the feed tempera- 
ture, they cannot properly be credited with 
that part of the work. The combined effi- 
ciency of boiler and furnace is naturally 
that fraction of the heat of the coal which 
has been absorbed by the boiler. Therefore 
since the heat already in the feed water is 
not supplied by the coal, except as a re- 
claimed and independently variable factor, it 
must play no part in our efficiency calcula- 
tions. And here is another fact that may 
strike us oddly. A boiler would show a 
slightly better theoretical efficiency on cold 
feed water. Again the reason is simple, be- 
cause the greater the difference in tempera- 
ture between the fire and the water in the 
boiler the more rapid will be the rate of heat 
transference, which will tend slightly to raise 
the efficiency in the case of using cold feed 
water. 



94 PREVENTING POWER-PLANT LOSSES 

Proper heating of the water supply to the 
boilers reduces the work imposed on them 
and consequently reduces the amount of coal 
consumed in like proportion, the combined 
efficiency of boiler and furnace remaining 
practically the same as with the colder water. 

This gain of over-all efficiency is calculable 
by comparing the heat added to the water 
with the heat necessary to generate steam 
at the existing steam pressure and the tem- 
perature of feed. 

For instance, if exhaust steam is utilized 
in a heater to raise the boiler water from say 
60 degrees to 210 degrees each pound of wa- 
ter receives 150 B.t.u. Now if boiler pressure 
is 125 pounds per square inch, the heat re- 
quired to make a pound of this steam from 
the old temperature of 60 degrees was 1,164 
B.t.u. We have therefore saved or reclaimed 
150 -'- 1,164 = 12.9 per cent of the heat for- 
merly required for the making of our steam, 
and this saving is directly reflected in a cor- 
respondingly great reduction in coal con- 
sumption. Approximately one per cent of 
the coal is saved for every 11 degrees we 
raise the feed water, providing this is accom- 
plished with heat otherwise wasted. The 
matter of exhaust-steam heating of the boiler 
feed is always included in a plant examina- 
tion, and frequently a substantial improve- 



THE BOILER PLANT 95 

ment is found possible in this direction, ow- 
ing usually to bad design in the plant itself. 
It is possible and also advisable when con- 
ditions are favorable to raise the feed water 
to a much higher temperature still by utiliz- 
ing or reclaiming some of the chimney loss 
from the boiler. This is accomplished by 
means of an economizer, consisting of a 
series of pipes installed in the path of the 
chimney gases, the feed water being pumped 
through the pipes in the opposite direction 
to the flow of the gases for promoting the 
most efficient transfer of the heat. This of 
course involves an expensive apparatus and 
its net value must be determined separately 
for each individual case. The water by this 
means may reach a temperature of 250 to 300 
degrees before entering the boilers, but as 
the efficiency of the economizer increases, 
the temperature of the chimney gases is re- 
duced. This together with the frictional re- 
sistance imposed upon the draft reduces the 
effectiveness of the chimney, and frequently 
to such an extent as to require the installa- 
tion of mechanical-draft apparatus, which 
of course adds to the expense and complica- 
tion of the plant. All of these factors must 
be carefully included in our calculation for 
ultimate commercial efficiency before a rec- 
ommendation of real value can be formed. 



96 PREVENTING POWER-PLANT LOSSES 

In the case of one client, for instance, I found 
that comparatively simple changes for the 
improvement of the combustion of the coal 
would give as great a saving as would have 
been possible with the more expensive appa- 
ratus. Frequently the improvement of the 
furnaces will reduce the chimney loss to such 
an extent that an economizer would have 
very little heat to reclaim. 

There are other instances where econo- 
mizers are plainly indicated by careful in- 
vestigation. Where it is for local reasons 
advisable to drive the boilers very hard, the 
economizer may result in a double saving 
that will be well worth while as a large pay- 
ing investment. Not only is a great part of 
the chimney loss reclaimed as. a direct saving 
of fuel, but at the same time the duty im- 
posed upon the boilers is radically reduced, 
thus bringing about two decided economies. 

The efficient handling of coal and ash is 
often an important matter. A careful study 
is made to determine exactly the amount of 
labor that could be saved by the installation 
of a proper conveying system, with all de- 
ductions made from the apparent saving to 
cover interest, maintenance, repairs, and la- 
bor connected with the project. The first 
cost and comparative efficiencies of different 
systems are taken into this consideration. In 



THE BOILER PLANT 97 

ash handling there are two principal methods 
employed: the mechanical conveyor 'and the 
air conveyor. In the latter a swift current 
of air is produced in a tube, either by means 
of a fan or by the employment of steam jets 
acting to induce the required velocity. There 
are many cases where a good investment can 
be found in these directions. 

It has been intended in these pages to set 
forth the methods employed for the determi- 
nation of preventable losses, and by illustra- 
tion from working cases to indicate to some 
slight extent the directness and effectiveness 
of these methods. It is quite aside from our 
present purpose to enter upon a discussion 
or even a fair description of the material 
aids in the production of the increased effi- 
ciency which is ever the goal of our efforts. 
The omission of a detailed treatment of 
equipment includes a very particular object. 
It is desirable for the purpose in hand to 
concentrate our attention upon those under- 
lying principles which govern the economy 
of every boiler plant in a manner entirely 
apart from, and absolutely independent of, 
the specific nature of its equipment or kind 
of operation to which this apparatus is sub- 
jected. With this in mind we have now seen 
how each loss that may occur in a boiler plant 
can be traced to its source and accurately 



98 PREVENTING POWER-PLANT LOSSES 

measured. We have seen how it is thus pos- 
sible with such a complete diagnosis to learn 
precisely what is wrong in the economy of 
any plant, and that the proper means for 
the saving of the preventable losses are in- 
dicated with equal clearness to the trained 
investigator. 

After an industrial boiler plant has been 
subjected to a thorough investigation, and 
after the subsequent changes in operation or 
in equipment have been made for the elimi- 
nation of waste, it then becomes necessary 
to render permanent this high efficiency and 
to prevent the plant from falling back into 
old ways and bad habits. This measure is 
particularly necessary in view of the fact 
that efficiency usually depends as much upon 
intelligent management as upon the excel- 
lence of equipment. This is especially true 
in the boiler plant, where bad management 
may reverse the savings of good apparatus 
into inefficiencies and continual waste. 

We shall therefore consider the means 
used to maintain high efficiency. A simple 
system is installed which results in accurate 
daily records of the amount of coal burned, 
the weight of water evaporated, the tempera- 
ture of feed water, and the pressure of steam. 
The last two figures are best obtained by 
means of automatic recording temperature 



THE BOILER PLANT 99 

and pressure gages. The coal and water 
may be weighed, preferably by automatic 
scales and recorders. Many different styles 
of water meters are on the market and a 
large number of these are worse than useless. 
But there are also a few excellent water 
meters and weighers which are practicable 
and reliable. 

A report blank is written up every night 
by the chief engineer, a copy of which is sent 
to the office, and this sheet shows the boiler 
horse power developed and the " equivalent 
evaporation per pound of coal as fired", to- 
gether with the number of boilers under 
steam, the other data previously mentioned, 
and any remarks by the chief engineer which 
may have direct bearing upon the efficiency 
that was obtained. By this record any fall- 
ing off of results is at once brought to the 
attention of the management, and calls for 
an immediate inquiry into the cause. After 
the equipment has once been made right, the 
cause of inefficiency can always be found 
either in the coal itself or in the handling 
of the boilers and furnaces. If an examina- 
tion of the coal does not show a falling off 
•in heat units or an increase in moisture of 
sufficient extent to account for the decreased 
evaporation on the report, then it is certain 
that the boiler-room staff is responsible for 



100 PREVENTING POWER-PLANT LOSSES 

the waste that has been exposed. Such de- 
fective operation is usually attributable to 
careless or ignorant firing, but may be partly 
chargeable to dirty boilers, leaky settings 
that have not been kept in repair, improper 
draft regulation, etc. 

Such a system can be further elaborated 
to such degree as local conditions and size 
of plant may warrant. Under appropriate 
circumstances an automatic combustion re- 
corder will prove a valuable adjunct to the 
daily record sheet. This device produces a 
continuous record of the C0 2 in the flue gases 
and therefore acts as an excellent check upon 
the handling of the fires for correct supply 
of air. 

With a daily system in its simplest form 
it will always be known whether the right 
number of boilers are in operation for the 
load that is carried. The lack of this knowl- 
edge alone leads many plants into excessively 
heavy coal bills. 

The form reproduced in Fig. 9 shows a 
daily report blank which I devised to suit the 
local requirements of one of my clients and it 
will serve as an illustration. 

The installation of an accurate accounting 
system for the boiler plant operates for the 
instruction of the engineer and fireman and 
enlists their interest in the work of produc- 



THE BOILER PLANT 



101 



ing economy such as no other means will ac- 
complish. Both humanity and efficiency are 
well served when a system of rewards is in- 
augurated to compensate the boiler-room 
staff for developing and maintaining a high 
evaporation as recorded on the daily re- 



DAILY BOILER REPORT 
C. F. SMITH & CO. NEW YORK CITY, N. Y. 
DATE 




Day 7 A.M. -5 P.M. 


Night 6 P.M. -7 A.M. 


Total Coal — - - — - - A 






Parts of soft coal - 






Water Evaporated - - B 






Actual evaporation per lb. of cual 








Temp, of Feed Water D 






Steam Pressure - - 






* Factor of Evaporation - - E 






*Equiv. Evap. from and at 212° „ 
(C xE)=F per lb coal - — - — F 






♦ Average B. H. P. Developed, Approx. .-.- 


E -4-330 


B 'r- 390 


Number of boilers fired - — - 














Number of boiler cleaned to-day 

if any - 














C02 - Chemists special report on combustion— 

Bemarks and Suggestions:- Engineer is requested to used this space. 
Quality of coal or any cause for poor results, repairs or 
trouble of any kind to be reported 

(Signed,. 

* These columns signify calculations which can be made In the office- 
but the engineer should check them. 



Fig. 9. Form for Daily Boiler Report 

ports. 1 Such reward is well deserved by the 
men, and can not easily be neglected by the 
management since the method reacts with 
large profits to their advantage in the re- 
duced coal bills. 

We have now seen that the efficiency of 
a factory boiler plant is definitely determin- 

1 See Evaporation Standards in Chapter X. 



102 PREVENTING POWER-PLANT LOSSES 

able by means of scientific diagnosis, that the 
balance of energy known as "loss" can be 
measured and analyzed, and that the large 
preventable portion of that loss can be re- 
claimed and added to the efficiency. As em- 
phasized by onr foregoing discussion, we 
have seen that for these accomplishments 
we are dependent upon the universal laws 
of the conservation of energy. 

So far we have dealt with the transforma- 
tion of the latent chemical energy of the coal 
into the active heat energy of combustion, 
which was again transmitted by the agency 
of the boiler into heat in the form of steam. 
From this point we proceed to the transfer- 
ence of this heat to the engine, and then its 
action in the engine by which a part of it is 
converted into mechanical work, thus repre- 
senting another cycle of efficiency. The in- 
vestigation of these matters, together with 
their bearing upon the location and elimina- 
tion of preventable losses as applied to the 
factory plant, will form the subject matter 
of our next discussion. 



Chapter V 

STEAM PIPING AND THE ENGINE PLANT 

T7R0M the boilers the steam is piped to 
■*- engines for power, to pumps and aux- 
iliary apparatus, and to systems for heating 
and process work. For the present we shall 
confine our discussion to that portion sup- 
plied directly to the engines. 

There is always a certain loss of heat from 
the steam on its way from the boiler to the 
point of its application. This loss is caused 
by radiation of heat from the steam piping 
and by energy used to overcome the friction 
of the steam against the inside surface of the 
pipe. The combined loss from both causes 
is manifested in condensation of a part of the 
steam and a reduction of pressure at the end 
of the pipe. 

In a well-designed plant these losses are 

very small. The condensation caused by 

radiation of heat to the surrounding air is 

minimized by properly covering the pipe with 

103 



104 PREVENTING POWER-PLANT LOSSES 

layers of heat-insulating material. In still 
air the radiation from a bare pipe with high- 
pressure steam may be computed by allowing 
a loss for each square foot of surface of from 
2 to 3 B.t.u. per hour per degree difference 
of temperature between the air and the steam 
in the pipe. This has been determined by 
experiment, but varies with conditions. The 
heat so radiated is not lost except in so far 
as our engine is concerned, but it is misspent 
energy used in raising the temperature of 
the air which envelops the pipe. Another 
method of determining the extent of this loss 
is by trapping and measuring the condensa- 
tion in the steam pipe and adding to this the 
entrained moisture in the steam, which is 
found by means of a steam calorimeter. 

The friction loss may be approximated by 
a comparison of the amount of heat in the 
steam at the initial and final pressures. A 
good covering will prevent about 85 per cent 
of the radiation loss. 

The reduction in pressure caused by fric- 
tion is lessened by shortening the pipe, in- 
creasing its diameter, and eliminating all 
possible elbows and turns. 

The total combined piping loss between 
the boilers and the engines may be very 
small, so that the heat delivered to the en- 
gine may be 98.3 per cent of the heat in the 



STEAM PIPING AND ENGINE PLANT 105 

steam produced by the boilers, which figure 
would represent the efficiency of the steam 
pipe correspondinng to our illustration in 
Chapter II. 

In some cases where long lines of piping 
are used and are badly laid out or improperly 
covered, the loss will be great; and in one 
plant that I investigated the preventable 
portion of this waste amounted to about 
$3,000 worth of coal a year. 

In addition to correct design and covering 
of piping it is possible to increase the saving 
by the employment of superheated steam. 
There are three kinds of steam. 1, Wet 
steam, which contains moisture in the vesic- 
ular state — that is, water in the form of 
fog. 2, "Dry saturated'' steam, which con- 
tains no moisture and has the temperature 
exactly corresponding to its pressure; this 
the layman calls "ordinary dry steam". 3, 
Superheated steam, which not only contains 
no moisture but carries more heat than would 
be accounted for by its pressure. It there- 
fore has a temperature above that of dry 
saturated steam, but the same pressure. Su- 
perheated steam is obtained by passing "or- 
dinary ' ' steam through specially constructed 
coils or tubes, surrounded by hot gases either 
from the boiler furnace or from a super- 
heater having a separate furnace of its own. 



106 PREVENTING POWER-PLANT LOSSES 

By such means it is common practice, where 
conditions warrant, to add from 100 to 200 
degrees to the temperature of the steam after 
it leaves the boiler. For special requirements 
very much higher temperatures can be added. 

The addition of heat to steam under pres- 
sure requires the expenditure of about 0.55 
B.t.u. 1 for each degree per pound of steam 
providing the steam had no moisture at the 
beginning, in which case the heat required 
is correspondingly greater since this moist- 
ure has also to be evaporated with the at- 
tendant input of its latent heat at the exist- 
ing pressure. 

In the case of piping steam to distant 
points, that part which reaches its destination 
as water is wholly worthless for doing work 
in the steam engine, although it has caused 
the consumption of as much fuel per pound 
as the uncondensed and therefore useful por- 
tion. Now by first passing our steam 
through a superheater, which in the given 
instance will absorb from the coal 55 heat 
units per pound of steam, we shall add 100 
degrees to its temperature. Since it is a 
property of steam that it will not condense 
until it becomes "'dry saturated" — that is, 

1 The specific heat of superheated steam varies with the pressure of 
the steam. Fifty-five heat units added to steam at 105-pounds gage pres- 
sure would add 100 degrees of superheat. 



STEAM PIPING AND ENGINE PLANT 107 

until it has lost its superheat — we may con- 
vey it in pipes and avoid condensation as 
long as any of the superheat remains. In 
good practice a degree of superheat will 
carry the steam 10 feet, so that if we desire 
to convey our steam 1,000 feet we should 
have to add 100 degrees to its temperature 
in order that its entire weight may be avail- 
able for use at the end of the line. 

The additional consumption of coal for 
securing the superheat must of course be 
deducted from the total saving of steam. 
This amount with a steam-gage pressure of 
101.3 pounds will be (55 -^ 1,16V) = 4.7 per 
cent of the heat required for a pound of the 
"dry saturated" steam. In the case of su- 
perheaters which are arranged inside of the 
boiler setting, less coal than this would be 
required for the reason that the additional 
heating surface would tend to increase the 
efficiency of the combined boiler and super- 
heater and to produce a smaller chimney loss. 
Consequently in ordinary superheating a 
very small percentage of fuel is required, 
and the saving by the stoppage of condensa- 
tion in long pipe-lines may be very large, 
depending entirely upon local conditions. 

Assuming now for the progress of our 

1 Heat in a pound of dry saturated steam at 101.3 pounds gage or 116 
pounds absolute above 60 degrees. 



108 PREVENTING POWER-PLANT LOSSES 

argument (as in Chapter II) that the pipe- 
line to our engine has an efficiency of 98.3 per 
cent, and (as before stated) that the boiler 
and furnace supplied to this line 58 per cent 
of the heat of the coal, then the engine will 
receive in the form of steam (0.983 X 0.58) 
= 57 per cent of the original heat in the coal. 

We are at present considering a fair type 
of factory Corliss engine running non-con- 
densing, and we have seen in our previous 
statement of analysis that of the heat it 
receives only about 7.3 per cent is converted 
into mechanical energy or work at the belt 
wheel or jack shaft. 

Now it might be assumed that so great a 
loss in this conversion from heat to work is 
principally chargeable to an inefficient de- 
sign of engine, but we shall see that this is 
not entirely true by comparing its efficiency 
with that of the most economical steam prime 
movers in existence. Take for example the 
highest type of steam turbines or compound 
engines operating on high-pressure super- 
heated steam and we find a maximum effi- 
ciency of about 24 per cent. At the present 
writing a 25,000 kilowatt steam-turbine elec- 
tric-generating set for one of the Chicago 
Public Service stations is being constructed, 
and this machine will be guaranteed to de- 
liver a kilowatt hour of electric current for 



STEAM PIPING AND ENGINE PLANT 109 

11.25 pounds of steam with an output of 20,- 
000 kilowatts. It will operate on 200 pounds 
pressure and 200 degrees of superheat, and 
an absolute back pressure of 1 inch of mer- 
cury. Assuming mechanical and electrical 
losses of 7!/2 per cent, a brake horse-power 
hour at the shaft will be produced for about 
7.76 pounds of steam. If the boilers produce 
7.76 pounds of steam under actual conditions 
per pound of coal at the turbine nozzles, then 
a mechanical horse-power hour will be ob- 
tained from one pound of coal, apparently a 
wonderful economy. But let us see just what 
this means in true efficiency. The number 
of heat units in a pound of the steam as 
supplied is 1,310 B.t.u., so that the total heat 
energy delivered per horse-power hour is 
10,165 B.t.u. Now since a horse-power hour 
is equivalent to 2,545 B.t.u. at 100 per cent 
efficiency, the actual efficiency developed is 
2,545 -=- 10,165 or 25 per cent. This repre- 
sents about the greatest achievement of the 
kind in modern steam-power development, 
and yet we have succeeded in converting into 
useful work only 25 per cent of the heat in 
the steam. By a little analysis we shall see 
how much further we are likely to attain 
toward higher efficiency. After the almost 
complete expansion of the steam in the highly 
developed turbine (or engine as the case may 



110 PREVENTING POWER-PLANT LOSSES 

be) it enters the condenser 1 , at which point 
it still contains 885 B.t.u. per pound. This 
large amount of heat is necessarily taken up 
by the circulating water of the condenser 
and is therefore worthless for the purpose 
of producing work. Therefore all the heat 
in the steam that could possibly be converted 
into mechanical energy with an absolutely 
perfect engine using this kind of steam would 
be 1,310 — 885, or 425 B.t.u., which is 425 -i- 
1,310 = 32.4 per cent of the total heat in the 
steam. This represents the ultimate effi- 
ciency of an ideal engine or turbine working 
under these almost ideal conditions. We may 
understand how nearly this limit has been 
approached by comparing the actual effi- 
ciency of 25 per cent that w^as obtained with 
what the perfect prime mover would develop, 
viz : — 32.4 per cent, and we see that the actual 
efficiency is 25 -=- 32.4, or about 77.2 per cent 
of a perfect result. That is to say, no mat- 
ter how we strive to improve the efficiency 
of turbines or engines, we could with a per- 
fect machine utilize only 32.4 per cent of 
the heat of the steam (at 200-pounds gage 
pressure and 200 degrees superheat) and we 

1 Vacuum created by condenser assumed at 96.6 per cent of a theoreti- 
cally perfect vacuum, i. e., an absolute pressure of 0.505 pounds per square 
inch or a 29-inch vacuum. Atmospheric pressure is 14.7 pounds per square 
inch at sea level. 



STEAM PIPING AND ENGINE PLANT 111 

shall have already reached 25 per cent with 
the new turbine we have mentioned. 

This narrow margin of theoretically pos- 
sible improvement is imposed by the fact 
that no matter how much we may improve 
our prime mover, the greatest portion of the 
heat of the steam (even when expanded to 
almost a perfect vacuum) will still be neces- 
sarily discharged to the condenser. This 
part of the heat is latent and is given up 
only upon condensation. 

Still higher pressures and temperatures 
of steam call for very expensive and special 
design of boilers, piping, and apparatus and 
the gain that can be looked for in these direc- 
tions is too small to make the attendant sav- 
ings of any considerable commercial value 
at the present cost of fuel. 

It is now plain that however much we im- 
prove the steam engine or turbine, its ther- 
mal efficiency will be low, the reason being 
that whether we operate condensing or non- 
condensing, with compound cylinders, multi- 
stage turbines, or with a simple Corliss en- 
gine, the greater portion of the heat (that is, 
the latent heat of steam at the exhaust con- 
ditions) will pass out to be absorbed by the 
condenser or to appear in the exhaust steam 
from the engine. 

It is now easy to understand why the effi- 



112 PREVENTING POWER-PLANT LOSSES 

cient utilization of exhaust steam is of pri- 
mary importance in the factory plant. It is 
also easy to see that a moderate-sized factory 
power plant so arranged, designed, and op- 
erated as to balance the production of ex- 
haust steam to the heating load, can develop 
an over-all efficiency much higher than the 
average large and highly refined plant of 
the public- service corporation. A failure to 
accomplish this balance in such a manner as 
to operate efficiently at different seasons of 
the year w T ill often make the cost of power 
so high that the central-station or water- 
power development will be enabled to offer 
prices for power which are competitive. Suc- 
cess in this matter depends upon a full knowl- 
edge of local conditions, obtainable only by 
such careful investigation as we are grad- 
ually describing; and this .knowledge to- 
gether with correct engineering information 
must form the basis of all plans and recom- 
mendations. 

An important question always to be de- 
cided is whether it will pay to run the engine 
condensing as opposed to exhausting into a 
heating system. If there happens to be a 
use for all of the exhaust steam all of the 
time this becomes a simple problem to solve. 
For illustration, take the Corliss engine of 
our example. If we add a condenser to pro- 



STEAM PIPING AND ENGINE PLANT 113 

cluce the ordinary vacuum of 25 to 26 inches 
we shall expect to reduce our 30 pounds of 
steam per brake horse-power hour to about 
22% pounds, thus making a saving of about 
25 per cent 1 of the steam and coal formerly 
used to run the engine. We shall also in- 
crease the horse-power capacity of the en- 
gine by the percentage which the vacuum 
adds to the mean effective or driving. pres- 
sure on the piston. This frequently amounts 
to one-third more power. For exact calcula- 
tions of these results each case must be sep- 
arately considered and proper allowance 
made for all affecting conditions. For the 
present purpose it is sufficient to state that 
under usual factory conditions the saving by 
condensing over non-condensing will be in 
the neighborhood of 20 to 25 per cent of the 
steam required per horse-power hour. 

1 For condensing — The heat in dry saturated steam expanding adia- 
batically from 101.3 pounds gage or 116 pounds absolute to 2 pounds 
absolute, i. e., running condensing (which corresponds to 25.85 inches of 
vacuum, is 265 B.t.u. The corresponding heat between the same initial 
pressure and 5.3 pounds back pressure or 20 pounds absolute is 132 B.t.u. 
That is, if perfectly utilized, steam of 101.3-pounds gage pressure will per- 
form a trifle over twice the work, if by adding a condenser the back pressure 
is reduced from 5.3 gage pressure to a vacuum of 25.85 inches of mercury. 

There are cases where this ratio of improvement has been realized by 
adding a condenser and inserting a low-pressure turbine between the engine 
and condenser, a turbine being intrinsically more efficient on low-pressure 
steam than a reciprocating engine. But the addition of a condenser alone to 
our simple engine will actually give an increase of power output of only 
about one-third, or a saving of steam for the same power of twenty-five 
per cent. These figures will vary considerably with the conditions such as 
initial steam pressure, mean effective pressure originally obtained, design of 
valve gearing, size of ports, condenser connections, etc, 



114 PREVENTING POWER-PLANT LOSSES 

If now we refer back to the heat in the 
exhanst steam from onr Corliss engine and 
remember that it contained 92.7 x per cent of 
the heat in the steam supplied to it, we shall 
observe that the expedient of employing a 
condenser will save in the form of energy 
only 20 to 25 per cent, and the balance of 
72.7 per cent to 67.7 per cent will still be 
wasted as discharge 2 from the condenser. 
Add to this the fact that an appreciable per- 
centage of steam is required to operate the 
condenser and the over-all efficiency will be 
still lower. 

If, on the other hand, we are able to con- 
nect the engine exhaust with an efficient heat- 
ing system, we shall be able to displace ex- 
pensive live steam from the boilers and util- 
ize practically all of the heat from the ex- 
haust steam. A good feed-water heater 
should form the first part of such a system. 
Now to complete our comparison of conden- 
sing versus heating with exhaust steam, let 
us see just what efficiency the engine is ca- 
pable of developing in the latter instance. 

We shall assume that the heating system 
and feed-water heater are so well designed 

1 88.1 per cent "dry saturated" steam and 4.6 per cent moisture at 228 
degrees. 

2 A small percentage of this can be returned to the boiler by adding a 
few degrees to the boiler water by means of a feed-water heater placed 
between the engine exhaust and the condenser. 



STEAM PIPING AND ENGINE PLANT 115 

that together they will utilize all the heat in 
the exhaust steam down to a drip tempera- 
ture of 200 degrees, and without for the 
present considering any piping loss, which 
may be very small or of considerable impor- 
tance as governed by local conditions. 

The heat in a pound of exhaust steam at 
5.3-pounds back-pressure that it will give up 
when cooling to 200 degrees at the drip end 
of heaters and radiators is 940 B.t.u. 1 This 
is 940 -=- 1,161 = 80.8 per cent of the heat 
entering the engine 2 or 940 -f- 1,076 = 87.3 
per cent of the heat in the exhaust steam, 
including its moisture. Of the heat entering 
the engine 7.3 per cent was converted into 
mechanical work, and by the perfect utiliza- 
tion of the exhaust steam we convert 80.8 per 
cent more of its heat into useful purposes 
(live steam of equal heat value would other- 
wise be required) so that the true efficiency 
of our ordinary Corliss engine has 'become 
7.3 per cent + 80.8 per cent = 88.1 per cent. 
There is no prime mover in the world that 
will even approach this efficiency, which is 



1 A pound of exhaust steam at 5.3 pounds gage pressure containing 
5 per cent moisture cooling to 200 degrees atmospheric pressure. In the 
steam 0.95 (1,156 — 168) = 938.6 B.t.u. 

In the water 0.05 (228 — 200) = 1.4 

Total heat given up per lb. of exhaust steam 940.0 B.t.u. 

2 Assuming dry saturated steam at the engine and computing heat 
above 60 degrees. 



116 PREVENTING POWER-PLANT LOSSES 

obtained as we have seen by balancing the 
production of exhaust to the heating require- 
ments with a simple type of steam engine. 
When we considered running condensing for 
this engine we found that we saved not over 
about 25 per cent, which brought its efficiency 
from 7.3 to 9.75 per cent, whereas by the above 
method of combining power with heating our 
efficiency becomes over 88 per cent. In prac- 
tice this works out so beautifully that for 
approximate calculations we may say that the 
efficient use of exhaust steam will take the 
place of an equivalent amount of live steam 
direct from the boilers. Thus we have seen 
a proper comparison of the value of running 
condensing as compared to heating with ex- 
haust steam when the heating load just bal- 
ances the production of the by-product ex- 
haust steam. So also have we confirmed 
the statement previously made that the aver- 
age factory plant has a great intrinsic ad- 
vantage over the central power-station where 
the former requires a considerable amount 
of heating. The figures 'for this comparison 
may be represented by a ratio as great as 
88 to 24, that is almost 4 to 1. When there 
is a smaller proportion of heating to be pro- 
vided for, this ratio varies accordingly and 
must be worked out carefully for any given 
case. As to condensing, the rough statement 



STEAM PIPING AND ENGINE PLANT 117 

that it will not pay if more than one-third 
of the engine exhanst can be used is approx- 
imately correct. 

If, under the operating conditions cited, it 
is desired to know the cost of producing 
energy or horse-power hours alone, the effi- 
ciency of the engine must be credited with 
the heat it supplies to the heating system. 
This ii equivalent in this case to crediting 
the engine with a (thermal) efficiency of 88 
per cent. 

This 88 per cent efficiency of a non-condens- 
ing engine exhausting into a perfect heating 
system as above stated is comparable to the 
24 per cent efficiency of the highly developed 
condensing steam turbine of the great and 
efficient central power plants. And this is 
the main reason why an isolated plant is able 
to compete successfully with power produced 
by the large central steam or water-power 
stations. 

This discussion strikingly exposes the 
necessity of including in our power-plant 
investigation a determination of the amount 
of steam used for heating as well as the 
amount consumed by the engines. These 
tests should include the power versus heat- 
ing requirements for summer and winter, day 
and night, in order to design for high effi- 
ciency at all times and under all conditions. 



118 PREVENTING POWER-PLANT LOSSES 

Where such determinations were made in one 
case I was enabled to add abont 50 per cent 
to the horse-power capacity of the plant with 
only an insignificant increase of steam from 
the boilers. In this instance this was accom- 
plished by converting a large amount of live- 
steam radiation into a low-pressure system 
which permitted the substitution of exhaust 
steam. The latter was then supplied by a 
Corliss engine which was installed to "take 
the work" out of the high-pressure steam be- 
fore it passed to the heating system. The 
engine merely acted as a reducing valve and 
the power obtained was a by-product of the 
revised heating system. 

There are many buildings and factories 
today that make steam for heating and pur- 
chase electric current for their power pur- 
poses but might just as easily obtain most 
of the power they need as a pure by-product 
of the heating system, with very little fur- 
ther expenditure for fuel; yet this fact is not 
widely understood outside of the engineering 
profession. The exact extent to which such 
results can be accomplished cannot be proph- 
esied or estimated without a very careful pre- 
liminary investigation of all affecting condi- 
tions along the lines we have indicated. 

In order to gain full information of these 
conditions it is necessary to test the engines 



STEAM PIPING AND ENGINE PLANT 119 

for steam economy. It will then also be 
known whether steam is being wasted by the 
engine in the form of exhanst that might be 
utilized, or in case of there being no oppor- 
tunity for this, to determine the saving pos- 
sible by reducing the waste in the engine 
itself. Even if the exhaust steam from one 
or more of the engines perfectly balances the 
heating load it is quite possible to discover 
waste and to cut down the consumption of 
steam of those engines in the plant which 
are run condensing. Economies of this kind 
react directly on the coal bill. 

The steam consumed per horse-power or 
kilowatt hour is found by measuring the feed 
water of the boilers supplying steam to an 
engine and at the same time taking indicator 
cards and noting the kilowatt hours pro- 
duced. In case of an engine exhausting into 
a surface type of condenser the exhaust con- 
densation can be measured instead of the 
feed water if this happens to be easier under 
the circumstances. From these tests we 
shall have the steam and coal 1 consumption 
in the engine as well as the fuel cost per 
horse-power or kilowatt hour, and we shall 
know how efficiently the engine is working, 

1 Coal consumption of the engine is obtained by combining with its 
steam consumption the evaporative results of the boiler tests discussed in 
Chapter III. 



120 PREVENTING POWER-PLANT LOSSES 

how much steam it is wasting, Avhat percent- 
age of its rated horse power it is developing, 
and consequently just what saving can be 
effected in steam and coal by making such 
repairs, changes in load, steam pressure or 
back pressure, etc., as will have been indi- 
cated by the results and data of our test. 

Sometimes a heavy back pressure 1 is found 
which when relieved by proper changes will 
increase the capacity of the engine 20 to 50 
per cent and also reduce the steam consump- 
tion materially by allowing an earlier cut-off. 
It is quite usual to find enough back press- 
ure. 2 on a non-condensing engine to reduce its 
horse-power rating from 12 to 25 per cent, 
and in one case I found, owing to heavy back 
pressure, sufficient steam in the exhaust to 
run twice the number of engines for the 
steam that was used. Trouble from this 
source is found by examination of indicator 
cards taken as part of the engine test. It 
is corrected usually by improvement in the 
exhaust piping or heating system, which is 

1 Back pressure is the pressure of the exhaust steam acting on the oppo- 
site side of the piston from the live steam that drives the engine. 

2 Effect of back pressure is proportional to the ratio of back pressure to 
mean effective pressure as found by the indicator. Thus if the mean 
effective pressure is 40 pounds and the back pressure 8 pounds, the capacity 
of the engine by relieving the back pressure will be increased 8 -J- 40 or 20 
per cent. For the same horse power this will permit an earlier cut-off in 
the engine with the attendant saving of steam. The effect of reducing back 
pressure is the same in kind as adding a condenser, the increase of efficiency 
varying only in degree. 



STEAM PIPING AND ENGINE PLANT 121 

frequently so poorly designed as to canse the 
congestion of steam resulting in back pres- 
sure on the engine. I have even found seri- 
ous back pressure caused by the sticking of 
the relief valve. This was remedied in five 
minutes and would never have occurred if a 
proper back-pressure gage had been attached 
to the exhaust pipe to indicate the existence 
of trouble. Sometimes back pressure is 
found to be caused in the engine itself due 
to its design in the provision of inadequate 
exhaust passages. The effect of this is espe- 
cially apparent when running at full capacity 
or overloads. 

If none of the exhaust steam from an en- 
gine can be used for heating purposes it then 
becomes the duty of the investigator to de- 
termine the extent and cost of savings that 
can be effected by changes in operation or 
by replacing the engine with one of more 
economical design. Since the test has given 
complete data as to the load to be carried 
and also as to the efficiency of the engine, it 
becomes possible to predict how much saving 
would be obtained by a more highly devel- 
oped type of engine whose economy is known. 
All items of cost, including any added operat- 
ing charges, must be taken into account so 
that the net saving on the investment can be 
determined. Such a report must review all 



122 PREVENTING POWER-PLANT LOSSES 

types of engines and turbines that are applic- 
able to the case in hand, and many impor- 
tant practical considerations must be in- 
cluded such as are connected with the opera- 
tion of the factory, the hours of running, the 
class of help at hand, the space available, 
and the steam pressure and condensing facil- 
ities both existing and possible. The cost 
and saving connected with the use of super- 
heated steam must enter into these compu- 
tations, both as applied to the present engine 
and to its possible use with the improved 
unit under consideration. Our engine test 
has given us a record of the variation of the 
load to be carried at all hours of the working 
day and this factor has important bearing 
upon our selection of a new unit. 

At this juncture let us emphasize the rela- 
tion of "load factor" to power-plant effi- 
ciency. "Load factor" is that percentage 
of its full rated output which a plant actually 
develops during a given period of time. In 
central-station practice the time period is 
considered 24 hours, though the load factor 
may also be determined for a 12-hour day. 
If a station is designed to produce 500,000 
kilowatt hours per day, but owing to the im- 
possibility of obtaining steady loads its ac- 
tual output is only 175,000 kilowatt hours, 
then its load factor is said to be 35 per cent, 



STEAM PIPING AND ENGINE PLANT 123 

a very common condition. Now it is obvious 
that when a plant so operates its investment 
charges per kilowatt hour will be almost 
trebled, and this indeed is the most serious 
problem with which the great power stations 
of today have to contend. Public service im- 
poses a widely variable load and includes 
such high "peaks" at certain hours of the 
day that the load factor is necessarily low. 
These variations in power requirements not 
only affect the investment charges, but im- 
pose an uneconomical kind of load on the 
engine or turbine equipment. 

To a large extent the average factory is 
free from the more serious part of such 
trouble, especially in regard to the load to 
be carried during the working day. There 
are exceptions to this rule, but in any event 
it is important to understand each case for 
the determination of best results, and our 
all-day test has given us such information 
that we can select the best sizes of engine 
for the work. An engine gives its highest 
efficiency at full load, falling off either with 
an increase or decrease from this point of 
the horse-power output. This relation of 
efficiency to capacity is generally clearly 
shown by a curve plotted with reference to 
a series of parallel determinations for the 
two values. This is known as the efficiency 



124 PREVENTING POWER-PLANT LOSSES 

curve and the characteristics of any kind of 
engine or turbine may be readily compared 
by this means which frequently facilitates 
a decision upon the best unit for the load con- 
ditions which latter have been disclosed as 
indicated. 

In our final specification of prime mover 
we must embody a due consideration for in- 
creased horse power to allow for growth of 
the factory plant. But this must be obtained 
with a minimum sacrifice of efficiency at other 
than full loads. To add somewhat of defi- 
niteness to this statement, we may, for in- 
stance, by the use of reliable efficiency curves, 
be enabled to discover that for some given 
size of unit a turbine will give better effi- 
ciency under a wide variation of load than 
a compound engine, although it may also be 
found that at a steady full load the engine 
would have the advantage. 

Without further discussion we shall realize 
that the thorough investigation of the engine- 
room part of our problem involves both 
broad and at the same time specific informa- 
tion, which is the result of decades of study 
and progress in this field. The subject is 
so great and so involved in its analysis that 
it would be quite aside from our present 
object to do more than make a few simplified 



STEAM PIPING AND ENGINE PLANT 125 

statements in a rather comprehensive man- 
ner. 

We shall therefore leave to the following 
chapter the review of efficiencies obtained 
with steam engines and the comparison 
with economies obtainable from other prime 
movers. 



Chaptek VI 

STEAM PIPING AND THE ENGINE PLANT 
(Continued) 

T ET us review the range of efficiencies 
■*—' obtained with steam engines, upon which 
we have already touched, and concentrate our 
attention upon the preventable losses in- 
volved, together with a comparison with 
those of other types of prime movers which 
enter the field of competition and which con- 
sequently demand our consideration. These 
other types include the internal-combustion 
engine whose fuels are oils and gases, the 
latter when derived directly from coal giving 
the name of "producer gas" to that specific 
kind of apparatus. To these we may also 
add the water-wheel or turbine. 

Beginning with the steam engine we have 
already observed that its efficiency varies 
between x and 25 per cent, considered purely 

1 The old slide-valve type will have efficiencies as low as 4 per cent. 
The coal used per engine horse power varies of course with the efficiency of 
the engine, the efficiency of the boiler and furnace, and the quality of the 
coal. In wide ranges of practice an engine will consume from about 1 or 13^ 
pounds of coal to 9 or 10 pounds per horse-power hour. 

126 



ENGINE-PLANT LOSSES 127 

as a power producer without reference just 
now to the utilization of its valuable by-prod- 
uct of exhaust steam. We have seen that 
even an ideal engine or turbine would not 
give an efficiency above 32.4 per cent with 
steam at 200-pounds pressure and 200 de- 
grees superheat, and that the efficiency is 
limited by the practicable amount to which 
we can increase the pressure and tempera- 
ture of the initial steam, these in turn being 
limited by considerations of design, safety 
and cost. The large necessary loss with the 
steam engine or turbine is occasioned by the 
discharge to the condenser of the exhaust, 
which even at highest obtainable vacuums 
contains the majority of heat units originally 
carried in the steam supplied to the prime 
mover. The principal partially preventable 
losses in the process are those due to friction, 
cylinder condensation, leakage, incomplete 
expansion of the steam, "wire drawing ", and 
excessive clearance volume. 

The losses due to friction in the best types, 
depending on their rating, amount to only 
about 5 per cent of the total power produced, 
which is a proportionately smaller percent- 
age when referred to the heat or energy in 
the steam. The percentage of frictional loss 
decreases as the horse-power output in- 
creases. It is reduced by careful design with 



128 PREVENTING POWER-PLANT LOSSES 

special regard to balanced valves and proper 
lubricating systems. 

The loss dne to cylinder condensation is 
the most serions of all, and is susceptible to 
the greatest reduction by improved design. 
It is caused by the chilling effect of the cylin- 
der walls of the engine upon the entering 
steam, and in simple engines using dry-sat- 
urated steam frequently accounts for 20 to 
25 per cent of their steam consumption. 
There are three methods of importance 
employed for reducing this loss : 

First, by increasing the horse-power rating 
of an engine, which is accomplished by the 
use of higher speeds and pressures and later 
"cut-offs". The percentage loss thus be- 
comes less since the condensation is an ap- 
proximately constant quantity. 

Second, by the use of superheated steam, 
which must be cooled to its saturation point 
before condensation can take place, it is made 
to act more nearly like a perfect gas with 
a consequently lower consumption by the 
minimizing of condensation. Under the right 
conditions the amount of coal required to 
superheat the steam is very small compared 
to the saving of steam thereby produced in 
the engine. This practice is much older 
abroad than in the United States, but is well 
established in this country and rapidly gain- 



ENGINE-PLANT LOSSES 129 

ing favor in manufacturing establishments. 
Economies are so decided in this direction 
that all modern central plants are employing 
superheat. Factory plants are able to obtain 
greater saving by its use than the more high- 
ly developed central stations. The reason is 
twofold. Factories usually require longer 
steam lines and therefore there is a good sav- 
ing possible in the reduction of piping loss. 
But the more potent fact is that the less effi- 
cient the engine the greater the cylinder con- 
densation, and consequently the greater will 
be the economy to be gained by superheating 
the steam which acts directly to reduce this 
loss. Steam of very high temperature re- 
quires the use of special design and material 
for piping and engine valves, but experience 
has indicated that a total temperature of not 
over 450 degrees to 500 degrees will not seri- 
ously affect an ordinarily well-constructed 
factory power plant. 

The third method of reducing the largely 
preventable cylinder condensation is by com- 
pounding our engine or turbine; that is to 
say, instead of performing the complete ex- 
pansion of the steam in one stage or cylinder, 
distributing the work consecutively among 
two or more cylinders of progressive size. 
Thus we have the compound engine (double, 
triple, or quadruple) according to the number 



130 PREVENTING POWER-PLANT LOSSES 

of stages of expansion which we provide. 
This step is advisable only when compara- 
tively high-pressure steam is available with 
its consequent high temperatures. The trans- 
fer of heat from steam to metal is propor- 
tional to the difference in temperature be- 
tween the steam and the metal. Hence when 
this difference is very great it pays to di- 
vide the expansion of the steam by com- 
pounding the cylinders so that each cylinder 
is kept at a temperature corresponding as 
nearly as possible to the temperature of the 
steam in that particular stage of its expan- 
sion. In this way cylinder condensation is 
reduced and a higher efficiency is obtained. 
It follows also that in such an engine super- 
heating the steam will have less effect than 
on a simpler type of steam motor. In fact, 
it is often possible to get compound-engine 
efficiency by combining superheat with a sim- 
ple engine, especially if the steam pressure 
is not high, that is not over about 125 pounds. 

In a number of cases it has been found that 
a low-pressure turbine can be attached to 
the exhaust of a steam engine with a large 
increase in horse power and efficiency. This 
is simply a convenient and efficient method of 
compounding and amounts to the addition 
of a second or third cylinder to the engine. 

Before leaving the subject of loss due to 



ENGINE-PLANT LOSSES 131 

cylinder condensation let ns emphasize an 
important point in this connection. Other 
things being equal, the larger the engine or 
turbine the greater will be its efficiency and 
the lower its steam consumption per horse- 
power hour. This follows from causes al- 
ready discussed, and permits appreciation of 
the fact that economy is produced by using 
a few large engines rather than a larger num- 
ber of small ones. In factory work it is fre- 
quently possible to secure large savings by 
following this plan. Otherwise stated, the 
development of mechanical energy by steam 
engines or turbines should be concentrated. 

This concentration as a general rule is lim- 
ited only by load conditions. For example, if 
a plant were to develop only one-third of its 
full load for a large portion of the time it 
would not ordinarily pay to try to operate 
with a single large engine. Either two or 
three engines suited to the conditions and 
thrown on as the load required would give 
better efficiency. On the other hand, if all the 
exhaust steam can be used all of the time, 
then it makes but little difference whether 
by scientific design we produce an engine 
horse-power hour for less steam. In such 
a case I have used a reducing valve for a 
Corliss engine when it- had to run at very 
light loads. This enabled the "chief" to 



132 PREVENTING POWER-PLANT LOSSES 

increase his steam pressure as the load in- 
creased. Without such precaution the en- 
gine valves would have "knocked", and 
"loops" or negative work would have oc- 
curred in the cylinder accompanied by regu- 
lation troubles. 

The engine problem can never be properly 
considered without reference to the use of 
its exhaust steam. 

In another factory plant I found the main 
engine to be about four times too large for 
the maximum load. In order to get it to run 
smoothly they had reduced the boiler pres- 
sure by 30 pounds. The result of both causes 
was a steam consumption of 80 pounds per 
horse power per hour and most of the ex- 
haust was being wasted. In this case it was 
necessary to recommend a smaller engine 
which would give an efficiency of 30 pounds, 
permit the use of full boiler pressure, and 
pay for itself in a short time. The great 
loss was due principally to cylinder conden- 
sation, most of which would be re-evaporated 
and wasted through the exhaust relief valve. 

The loss due to leakage is an important 
one. This occurs through the steam valve 
or past the piston, so that live steam escapes 
through the engine into the exhaust piping 
without doing any work. This kind of waste 
is very serious and I have found losses of 



ENGINE-PLANT LOSSES 133 

many tons of coal from this source. The cor- 
rection is usually a machine-shop job involv- 
ing reboring of the cylinder, new piston 
rings, new piston, or replannig of valve and 
seat according to the precise location of the 
trouble. In a large measure it can be pre- 
vented in the original specification of engines 
by avoiding those types, especially most de- 
signs of high-speed four-valve or automatic 
engines, which are intrinsically wasteful in 
regard to leakage after they have been run 
a few months. In a recent test I found an 
engine of this class using 57 pounds of steam 
per horse-power hour where 30 pounds 
should have been sufficient. The principal 
part of this loss was due to leakage past the 
steam valve. 

The loss from incomplete expansion of the 
steam may be caused by the lack of intelli- 
gent specifications in the purchase of the en- 
gine. That is to say, many engines are pur- 
chased "on faith" with no proper provision 
as to their size, speed, cut-off at full load, or 
steam consumption. Thus it is possible to 
buy an engine guaranteed to develop say 200 
horse power. This may easily result in the 
purchase of an engine which should properly 
be rated at 125 horse power. It will develop 
200 horse power, but only at the expense of 
a late cut-off which means an excessive steam 



134 PREVENTING POWER-PLANT LOSSES 

consumption. Unfortunately this is not an 
uncommon occurrence. The waste of steam 
is due to incomplete expansion caused by in- 
sufficient cylinder volume. 

The excessive overloading of an engine 
properly purchased also prevents complete 
expansion and results in waste. This occurs 
in the rapid growth of factory power require- 
ments the extent of which is not realized by 
the management. 

Wire drawing is the term applied to the 
reduction in pressure occasioned by the pas- 
sage of steam through a restricted port. By 
its action the initial steam pressure, act- 
ing on the piston of the engine, becomes 
less than the pressure at the throttle. The 
effective pressure of the working stroke is 
thus reduced, with a corresponding increase 
in the steam consumed per horse-power hour. 
This loss should be reduced to a minimum 
by the designer of the engine as very little 
can afterwards be accomplished for its cor- 
rection. 

The last in our list of preventable losses 
is that due to excessive clearance volumes 
in the cylinder and steam passages. When 
the engine is on dead centre the space en- 
closed by the piston, the cylinder head, and 
the steam and exhaust valves is called the 
1 ' clearance ' \ Evidently this space must be 



ENGINE-PLANT LOSSES 135 

filled with steam before full pressure can be 
exerted on the piston. The live steam so used 
is wasted as compared to the operation of 
an ideal engine which would have no clear- 
ance space. By scientific design the clear- 
ance is made as small a percentage of the 
total cylinder volume as possible, and in op- 
eration a high "compression" may be car- 
ried in order to fill the clearance space with 
exhaust instead of live steam. 

Now if the investigation of our plant has 
shown that none of the methods thus far dis- 
cussed will yield the desired results in lower 
cost of power, we can still turn to other 
means. 

The internal-combustion engine includes 
oil, producer gas and natural gas as fuel, 
which in each case is burned inside of the 
engine cylinder. The heat thus developed 
causes pressure which acts in place of steam 
against the piston. 

If we already have a steam plant a part 
or all of which must be run to meet imposed 
requirements, then the addition of another 
type of power unit will add complications 
which are well to avoid unless great economy 
demands them. This is especially true in 
manufacturing where the product and not 
power is the first consideration. Therefore 
in most cases it does not pay to employ two 



136 PREVENTING POWER-PLANT LOSSES 

kinds of power. Such a change would usu- 
ally add labor and interest charges far out 
of proportion to those required for an equal 
increase in power by a steam-driven unit. 
Furthermore the internal-combustion engine, 
although it has undergone great improve- 
ment in recent years, lacks the decided ele- 
ment of reliability that can rightly be attrib- 
uted to the steam engine. 

But there are still many cases where the 
gas engine is an economic proposition. Not- 
ably we may mention those manufacturing 
localities where cheap natural gas is avail- 
able, where I have tested many engines giv- 
ing excellent service, both as to reliability 
and economy. Then there is a growing field 
of usefulness where the gas engine is em- 
ployed to operate on the by-product gases 
from the blast furnaces and coke ovens of 
the steel industry. 

The producer-gas engine is applicable in 
small plants requiring very little steam and 
where an occasional shut-down or a duplicate 
engine would be considered. 

The oil engine has the advantage over pro- 
ducer gas in that the engine itself consti- 
tutes the entire plant and does not require 
an additional apparatus for producing the 
gas. 

The cost of power with any of the internal- 



ENGINE-PLANT LOSSES 137 

combustion engines depends upon the same 
factors that govern any other means of 
power production, viz: — Efficiency, cost of 
fuel, labor and interest charges. The last 
two factors must be determined separately 
for any individual set of conditions. Effi- 
ciency and cost of fuel we shall now examine. 
In practice, depending upon load and other 
conditions, the Diesel type of internal-com- 
bustion engine when operating on oil fuel will 
develop an efficiency of 25 to 27 per cent. 
Under best conditions about 31 per cent has 
been obtained. Thus if the heat value of the 
oil used was 20,000 heat units (B.t.u.) per 
pound, the engine used 0.41 x pounds of oil 
for each brake horse-power hour generated. 
Other highly developed oil engines attain 
these efficiencies. The oil consumption will 
vary with the percentage of full load carried, 
but with a well-designed high-pressure four- 
cycle engine 0.6 pounds of oil of the above 
heat value may be taken as a fair estimate of 
practical performance. If the fuel costs 2% 
cents per gallon containing 7% pounds, then 
the cost of oil per brake horse-power hour 
will be $0,002 2 , that is two mills. 

Fuel used = x 

Then x (0.31 X 20,000) = 2,545 

x = 0.411. 

0.6 

"0.002 



138 PREVENTING POWER-PLANT LOSSES 

This is not necessarily lower than the fuel 
cost with a steam engine using coal, for the 
comparison depends entirely upon efficiencies 
and fuel prices. A brief comparison may not 
be amiss at this point. With low-grade coal 
like anthracite buckwheat, a properly de- 
signed boiler plant will give 1,000 pounds of 
steam at a fuel cost of 11 cents. (I have a 
very small plant doing this for 10 cents.) A 
good compound engine or turbine will give a 
horse-power hour for 15 pounds of steam, 
which at this price gives a fuel cost per horse- 
power hour of $0.00165, that is 1.65 mills, 
which is even lower than the oil-engine fuel 
cost just cited. There are plenty of manu- 
facturing plants where the cost of fuel per 
horse-power hour will run from 5 mills to 
iy 2 cents, and great savings are generally 
possible, but by methods that can be indi- 
cated with certainty only by a thorough in- 
vestigation of all the surrounding conditions. 

The efficiencies of the best types of inter- 
nal-combustion engines designed to operate 
on the Otto or four-stroke cycle x will range 
between 16 and 24 per cent. When they are 

1 Four strokes of the piston or two revolutions for each explosion or 
power stroke. Order of cycles: 1, explosion stroke outward; 2, piston 
returns to dead centre expelling gases of combustion to exhaust; 3, suction 
stroke outward taking in fresh charge of gas and air; and 4, compressing 
same preparatory to firing for the first or power stroke. In the two-cycle 
engines all four functions are performed in two strokes with an explosion 
every revolution. 



ENGINE-PLANT LOSSES 139 

supplied with gas from a " producer " their 
individual efficiencies remain about the same, 
but the over-all or ultimate efficiency is re- 
duced by the loss in the producer itself. The 
producer efficiency may be said to be about 
80 per cent, so that if the engine has an effi- 
ciency of 20 per cent the ultimate efficiency 
in the use of the fuel will be 0.20 X 0.80 or 16 
per cent, based on the heat in the coal sup- 
plied to the producer. 

In the natural gas regions I have found 
gas engines using from 10 to 12 cubic feet of 
gas per indicator horse power per hour with 
gas of 1,100 B.t.u. per cubic foot selling at 
20 cents per 1,000 cubic feet. In these cir- 
cumstances an engine may develop a brake 
or mechanical horse-power hour for 11 cubic 
feet of gas, in which case the fuel cost 1 would 
be about $0.0022. (The heat efficiency of the 
engine would be 21 per cent.) This is a fair- 
ly low figure in manufacturing work, but it 
must be remembered that in many localities 
where gas is cheap high-grade coal may also 
be obtained at very low prices. Furthermore, 
in the many cases where a considerable 
amount of heating is required, the steam en- 

11 X $0.20 

1 Fuel cost = = $0.0022 per b.h.p. hour. 

1,000 

Assuming 90 per cent mechanical efficiency, i. e., 10 per cent friction, 
a consumption of 10 cu. ft. per indicator horse-power hour will become 
1.00 ■£- 0.90 X 10 = 11.1 cu. ft. per. brake horse-power hour. 



140 PREVENTING POWER-PLANT LOSSES 

gine by the utilization of its valuable exhaust 
steam may not only be enabled to compete 
with the gas engine but may produce a much 
higher over-all efficiency. 

It is true that the gas or oil engine also 
possesses a similar feature of by-product 
heat supply, but not to the extent of the fac- 
tory type of steam engine. Eeferring back 
to our previous analysis we shall remember 
that the exhaust steam from a good Corliss 
engine may contain over 90 per cent of the 
original heat in the steam supplied at the 
throttle. By its efficient utilization its ex- 
haust may be made to take the place of nearly 
an equal weight of live steam from the boil- 
ers, in which circumstance the over-all ef- 
ficiency thus produced is extremely high. 

In order to understand the nature of the 
by-product heat from our gas engine we may 
profitably consider the typical heat balance 
on page 141. This analysis may fairly be 
taken as representative of the best gas-engine 
practice and we shall take for the example 
the engine recently mentioned. 

An examination of this analysis at once 
shows where the principal losses occur in 
the operation of a gas engine. The great- 
est loss and the most tangible one is the heat 
carried away in the jacket-water used for 
the purpose of maintaining the cylinder at 



ENGINE-PLANT LOSSES 



141 



GAS-ENGINE HEAT BALANCE 

Heat in 1 cubic foot of natural gas . 1,100 B.t.u. 

Heat supplied by 11 cubic feet of 
gas to produce a brake horse 
power per hour— 11 X 1,100 12,100 B.t.u. 

Heat equivalent of 1 brake-horse- 
power hour 2,545 B.t.u. 

Heat efficiency of engine 2,545 -s- 

12,100 = 21 per cent 



Heat supplied to engine per 
brake-horse-power hour in 11 


B.t.u. 


Per cent 


cubic feet of gas 


12,100 


100 






Heat converted into mechanical 






or useful energy (efficiency) . . . 
Heat absorbed by jacket water. . 
Heat absorbed in friction with a 


2,545 

5,082 


21.0 
42.0 


mechanical efficiency of 90 per 
cent. 






2,545 B.t.u. -T- 0.90 X 0.10 






= 283 


283 


2.3 


Heat discharged in hot exhaust 
gases and losses due to radia- 






tion and incomplete combus- 
tion 


4,190 


34.7 






Total 


12,100 


100.0 



a safe working temperature. This cooling 
water may enter the cylinder at a probable 
temperature of 60 degrees, and in practice is 
drawn off at about 100 to 120 degrees. It is 
better, however, for gas consumption to 
maintain a higher jacket temperature. I have 
increased the horse power of a factory gas 
engine 11 per cent by maintaining a tern- 



142 PREVENTING POWER-PLANT LOSSES 

perature between 170 and 180 degrees. The 
practicability of this measure depends large- 
ly upon the design of the engine, although 
the deposit of impurities from the water 
might in some cases cause trouble. In ex- 
perimenting on another make of engine no 
increase of power was gained, for the evident 
reason that in that particular case the gas 
inlet valve also became heated, thus increas- 
ing the specific volume of the gas so that the 
cylinder received a less weight of fuel per 
stroke, and so offsetting the gain that could 
otherwise have been expected. 

Furthermore, in factory work it is usual to 
provide an over-abundant supply of cooling 
water to prevent possible trouble. This could 
be managed by automatic regulation of the 
cooling water, but no great advance has been 
made in this direction. The warm jacket 
water, even at the usual moderate tempera- 
tures, may however be used for heating pur- 
poses and this is sometimes done. But since 
it is about 100 degrees below the temperature 
of exhaust steam, a relatively large heating 
surface must be employed to obtain good ef- 
ficiency. With a properly worked-out heat- 
ing system a considerable fraction of the 
jacket-water loss may be reclaimed and cred- 
ited to the gas-engine's efficiency if condi- 
tions admit of such a plan. 



ENGINE-PLANT LOSSES 143 

The remaining large waste is the last item 
in the preceding analysis. By far the great- 
est portion of this, in all probably 30 per 
cent, may be accounted for by the heat car- 
ried out in the exhanst gases. This heat 
may be partially conserved by the nse of a 
heater or low-pressure boiler through which 
the engine exhaust is made to circulate, thus 
giving up heat to raise the temperature of 
the contained water or to produce a limited 
amount of low-pressure steam which may be 
utilized in any convenient manner. Various 
proposed plans have included hot-water or 
steam heating, and even the propulsion of a 
condensing steam turbine by means of the 
steam resulting from the hot exhaust gases. 
But this matter of heat reclamation as per- 
taining to the internal-combustion engine is 
neither so simple nor so widely practised 
as in the case of the steam engine whose ex- 
haust is so readily and effectively applied to 
heating purposes. Practically all the waste 
heat from the steam engine is discharged 
through the exhaust pipe and is contained in 
one form only, whereas the gas engine wastes 
its heat both through its exhaust pipe in the 
inconvenient form of hot gases, and also 
through its cylinder walls, appearing in the 
form of warm water usually of insufficient 



144 PREVENTING POWER-PLANT LOSSES 

temperature to be especially suitable for 
beating purposes. 

"Producer gas" is made from coal sup- 
plied to a special retort or producer in wbicb 
a moderate temperature is maintained. The 
volatile gases of tbe coal are first expelled 
and collected in a gas tank. Tbe remain- 
ing incandescent carbon is tben treated with 
steam to form water gas, which mingles with 
the volatile or "coal gas" and the mixture 
thus formed is known as "producer gas". 1 

The process of making this gas is not per- 
fect. The losses are principally due to radi- 
ation of heat, unused carbon discharged in 
the ash, the presence in the gas of surplus 
oxygen, and the formation of C0 2 . The re- 
sult is that the gas produced contains only 
about 80 per cent of the heat value of the 
coal used for its production. Consequently 
an engine of 20 per cent efficiency using gas 
from such a producer will give an over-all 
efficiency of 0.20 X 0.80 = 16 per cent, as be- 
fore stated. That is, 16 per cent of the heat 
in the coal will have been converted into use- 
ful mechanical work and the total loss will 
have been 84 per cent. 

1 Producer Gas: The volatile portion of the coal is made up of hydro- 
carbon gases, largely CEU and similar groups. The water gas consists of 
CO and H2, the reaction being C + H2O = CO + H2. A certain unavoid- 
able percentage of CO2 and O dilutes the gases and reduces their heating 
value. 



ENGINE-PLANT LOSSES 145 

A producer-gas plant that develops an ac- 
tual horse power per hour for one pound of 
coal under operating conditions is doing very 
fair work. 1 

The fuel economy of the producer-gas 
plant has had a very desirable effect on de- 
signers and manufacturers of steam equip- 
ment. The Germans have made great prog- 
ress in the development of small-sized steam 
plants which have been given the name of 
" Locomobiles ". These are now manufac- 
tured in the United States. Such an equip- 
ment consists of a well-designed engine 
mounted directly on top of an internally fired 
boiler with provision for highly superheat- 
ing the steam. To reduce cylinder conden- 
sation the engine cylinders are continually 
bathed in the hot chimney gases discharged 
from the boiler. There is practically no 
steam piping between engine and boiler, and 
every detail is so arranged as to concentrate 
and conserve to the greatest possible ex- 
tent the heat involved. The result is that a 
horse power per hour has been produced for 
approximately one pound of coal, thus prac- 
tically equalling the producer-gas equipment 
in fuel economy. 

In the large refined central station of re- 

1 If the coal used has a calorific value of 13,000 B.t.u. per pound, the 
over-all efficiency in this case is 2,545 -5- 13,000 = 19.6 per cent. 



146 PREVENTING POWER-PLANT LOSSES 

cent design it is also possible to generate 
a horse-power hour of energy for close to a 
pound of good coal, so that when the most 
highly developed types of each are consid- 
ered the internal-combustion engine cannot 
show any marked saving in fuel over the 
economy of the steam engine. In factory 
work the question of heating is important, 
and in this field the steam engine is highly 
adaptable. But each problem must be sep- 
arately analyzed and decided in accordance 
with its local conditions, and first cost and 
reliability must be considered. 

Before leaving the engine-room depart- 
ment of our investigation the reader would 
perhaps feel disappointed if some reference 
were not made to the present rivalry which 
in a certain way exists between the recipro- 
cating steam engine and the steam turbine. 
A few years ago there was a prevalent 
opinion, based on the performances then ob- 
tained, that in general the reciprocating en- 
gine was the more efficient for high steam 
pressures and that the turbine gave the bet- 
ter results on low pressures. It was also an 
opinion of the times that in sizes under about 
1,000 kilowatts the engine would give higher 
efficiency than the turbine. While it is still 
true that there are intrinsic reasons why the 
turbine is more efficient on low pressures, yet 



ENGINE-PLANT LOSSES 147 

the turbine has made such rapid improve- 
ment in design during the last five to seven 
years that its position relative to the recipro- 
cating engine has considerably altered. It 
is now possible to equal engine efficiency in 
turbines of 500-kilowatts capacity and even 
considerably less. In the very small sizes, 
i. e., from 30 to 100 kilowatts, especially non- 
condensing, the engine has the advantage in 
steam economy. Owing to the continual ad- 
vance in steam turbines, improvements in re- 
ducing gears, smaller floor-space require- 
ments, absence of oil in exhaust steam, etc., 
it is not always possible to decide a case of 
engine versus turbine on a small difference 
in fuel consumption alone, especially in the 
moderate sizes. Again it is necessary to re- 
fer back to local conditions of operation. For 
instance, if all our exhaust steam were to be 
utilized in any case, a few pounds greater 
consumption on the part of the turbine would 
make no economic difference. On the other 
hand, if coal were dear, condensing imprac- 
ticable, and sufficient heating requirements 
were unavailable for utilization of the ex- 
haust steam (considering moderate or small 
size of unit) the steam engine would win the 
case, other things being equal. Since condi- 
tions of operation including steam pressure, 
superheat, condensing facilities, size of unit, 



148 PREVENTING POWER-PLANT LOSSES 

cost of fuel, heating requirements, etc., so 
largely govern the selection of prime mover, 
it is safer to make no further statements than 
those already indicated. 

We have yet to consider the water turbine 
as a factor in our engine problem. In only 
limited localities are factories able to make 
direct use of the water turbine, the modern 
development of one type of the old-time mill 
wheel. In most cases, however, the water 
turbine has only to be considered indirectly 
as a means for the production of "outside 
power" for sale by electric power companies. 
Incidentally a modern water wheel or turbine 
ranges in efficiency from about 70 to 90 per 
cent. That is to say, in the latter case only 
10 per cent of the energy in the falling water 
would be misspent or wasted. In many sec- 
tions of the country the question of the value 
of purchasing power from an outside source 
as opposed to the production of power in the 
industrial plant itself constitutes a problem 
of growing importance. Such outside power 
may be generated hydraulically, or by water 
power combined with an auxiliary steam 
plant, or by a steam plant alone. The method 
of determining its value to the factory owner 
will be the same in any of these cases, pro- 
viding the factor of reliability is always 
equal. 



ENGINE-PLANT LOSSES 149 

Local factory conditions so vitally affect 
the cost at which power may be produced 
that without an individual investigation it is 
impossible to state whether a plant would 
reduce or increase its expenses by purchas- 
ing outside power at any proposed rate. The 
two most important of these factors are: 1, 
possible use for exhaust steam for heating 
or process work as compared to steam re- 
quired for power production ; and 2, cost and 
quality of coal available. 

Knowledge of the first factor must be thor- 
ough. It must be determined how much ex- 
haust steam under improved conditions can 
be used at all seasons of the year for both 
the day and night runs. The amount of live 
steam demanded by the engine must be simi- 
larly determined. Only by this means will 
it be possible to learn the true average cost 
of power. The necessity of this measure 
will be understood by reference to our fore- 
going discussion on the value of exhaust 
steam for heating as compared to live steam. 

In order to demonstrate this relation to 
the owners I once shut down all the engines 
in a large plant and continued the heating 
with live steam. (The exhaust steam from 
the engines had previously supplied the heat- 
ing system.) They were astounded to find 
that the same quantity of fuel was burned 



150 PREVENTING POWER-PLANT LOSSES 

with the engines all stopped and the boilers 
carrying the heating load only. If outside 
power had been installed for the machinery 
no saving in coal would have resulted. 

When the heating accomplished by the ex- 
haust steam is deducted from the fuel re- 
quired to operate the engines, the balance 
only is chargeable to power, and such is the 
method required in order to obtain a true 
and fair comparison of the cost of operation 
with purchased power for running the ma- 
chinery and with boilers reserved for heat- 
ing. 

A certain part and sometimes all of the 
boiler plant will be needed for heating even 
when outside power is used. The fixed and 
operating charges on this portion of the 
boiler plant are therefore directly charge- 
able to the heating system and not to the en- 
gine plant in estimating power costs. When 
the true cost of power per kilowatt hour (on 
the switchboard) has been worked out for 
conditions as found, it then becomes neces- 
sary to determine what this cost would be if 
the plant were improved and all preventable 
waste reclaimed. This improved or possible 
power cost is based upon the complete data 
obtained in the boiler and engine-plant sec- 
tions of our investigation thus far outlined, 
with due reference to the heating-system ex- 



ENGINE-PLANT LOSSES 151 

animation which will be discussed in the fol- 
lowing chapter. 

Assume now that the possible cost per kilo- 
watt hour has been determined, including all 
charges for recommended changes. This cost 
is not directly comparable to the kilowatt- 
hour cost as quoted by the electric-power 
company. To the latter 's figure must be 
added the charge per kilowatt hour of that 
part of the time of the factory engineer and 
assistants which is chargeable to power 
alone since their services are not eliminated 
by the use of outside power. This point is 
usually overlooked, and as it often makes a 
marked increase in the true cost of the pur- 
chased power it is not usually mentioned by 
its promoters. This subject of central-sta- 
tion current will be treated more fully in a 
later chapter. 

The engine room of every factory should 
be equipped with a simple system of daily re- 
ports designed to meet the conditions of the 
plant. Duplicate copies covering the last 
twenty-four hours should be filed each morn- 
ing in the office of the manager and in the 
records of the operating engineer. A sample 
of a report blank made for the requirements 
of a client is shown in Fig. 10. The results 
to be obtained by the use of such a system 
are: 



152 



PREVENTING POWER-PLANT LOSSES 



1. The establishment of an intelligent and 
economic relation between the management 
and chief engineer. 



DAILY ENGINE ROOM REPORT 
DATE 




Day 7 A.M.-6P.M 


Night 6 P.M.— 7 A.M. 


Main engine hours running 






Small engine hours running . 






K. W. H. Main Engine . 






K. W. H. Small Engine 






Total K. W. H ._ . .. 








♦Coal per K. W. H 






Maximum K. V. A. during run 






Heating Live 






H t r E h 








Remarks: - Engineer is requested to use this space for reporting any matter needing 

Signed, 

Engineer. 

♦The main engine should use not over 4.3 -lb. coal per K.W H. at 7- lb. actual 
evaporation and the small engine 6.4- lb. coal, surplus being chargeable to live steam 
heating and to pumps. 



Fig. 10. Form for Daily Engine-Room Report. 



2. A working knowledge of the plant that 
would not otherwise be obtained, including a 
means for estimating the cost of power. 

3. The computation of the efficiency of the 



ENGINE-PLANT LOSSES 153 

engine plant (the boiler plant being already 
under a system described in Chapter III). 

4. Where the engines have been individual- 
ly tested, the amount of live steam required 
for heating and process work may be calcu- 
lated. 

This record blank is in use in an electrical- 
ly operated plant, but it can be modified for 
belt-driven practice. 

During the investigation of the plant the 
engines were individually tested for steam 
and fuel consumption per horse-power and 
kilowatt hour. The kilowatt hours are ob- 
tained daily, and this information combined 
with the evaporation record of the boiler 
plant enables the engineer to compute just 
what portion of the total steam produced is 
used for pumps and live-steam heating. 



Chapter VII 
THE HEATING SYSTEM 

A GEEAT waste of steam and fuel in man- 
■**- nfacturing plants is directly charge- 
able to inefficient heating systems. To most 
lay minds the term " steam heating" affords 
merely a picture of radiators or pipe coils, 
having connections for steam and drip lines, 
with possibly a supplementary idea that if 
the condensed steam is returned to the boiler 
the efficiency will be high and that there the 
matter ends. 

If it truly ended so simply and happily 
there would be no excuse for the present dis- 
cussion. As a matter of fact, however, I 
have found heating systems using three 
pounds 1 of steam where one pound would 
have accomplished the same result. In other 
cases I have discovered heating arrange- 
ments intended for exhaust steam so badly 
designed that costly live steam had to be used 

1 The term "pounds" refers not to steam pressure but to weight of 
steam used. 

154 



THE HEATING SYSTEM 155 

instead, while more than enough exhaust 
steam to heat the entire plant was being 
wastefully blown out of the relief valve. It 
is from such cases as this that the uniniti- 
ated have formed the opinion (and it is hard 
to dislodge) that live or high-pressure steam 
is far superior to exhaust steam for heating 
purposes. 

It was shown in Chapter IV that the ex- 
haust steam from a Corliss engine working 
under ordinary factory conditions contained 
92.7 per cent of the heat present in the live 
steam at 101.3-pounds gauge pressure, and 
that the engine absorbed only 7.3 per cent 
of the heat contained in the original steam. 
A more striking comparison is that between 
the heating values of high- and low-pressure 
steam without regard to the action of an en- 
gine. The following table gives the desired 
figures: — 

Heat above 60 degrees in 1 pound of 
steam at 101.3-pounds gauge pres- 
sure —1,161 B.t.u. 

Heat above 60 degrees in 1 pound of 

steam at 5.3-pounds gauge pressure. — 1,128 B.t.u. 

Heat above 60 degrees in 1 pound of 

steam at 0-pounds gauge pressure. . — 1,122 B.t.u. 

Heat above 60 degrees in 1 pound of 
exhaust steam, including 5 per cent 
moisture at 5.3-pounds gauge pres- 
sure, from example of engine in 
Chapter IV —1,076 B.t.u. 



156 PREVENTING POWER-PLANT LOSSES 

From this we may see that a pound of 
steam at zero gauge or atmospheric pres- 
sure contains within 3y 2 per cent as much 
heat as the same weight of steam at 101.3- 
pounds pressure. 

A board of directors found it difficult to 
believe that exhaust steam from the engines 
could actually accomplish about 90 per cent 
as much heating as live steam direct from 
the boilers. They asked me if it were true 
that a producer-gas engine could produce a 
horse-power hour from a pound of coal. To 
this I answered "Yes." Their next ques- 
tion was, "How much coal per horse-power 
hour do our present (old slide-valve) en- 
gines require?" I stated this amount to be 
between 5 and 7 pounds. "Why then," they 
demanded, ' ' can we not make our power with 
a gas producer and save 4 to 6 pounds of 
coal per horse-power hour!" I reminded 
them that all the exhaust steam was being 
used, and that even if they eliminated all the 
steam engines they would still have to burn 
about 90 per cent as much fuel to make suf- 
ficient live steam for the heating require- 
ments alone. In addition to this there would 
be the coal consumed by the producer equip- 
ment, and no saving would result. 

This did not appeal to them, so I planned a 
demonstration which proved to be convinc- 



THE HEATING SYSTEM 157 

ing. (This was briefly referred to in the last 
chapter.) I shut down every engine in the 
plant and weighed the fuel to the boilers 
whose load was heating only. The result was 
that no perceptible difference in fuel con- 
sumption was noted, much to the surprise of 
the interested officials. Needless to say, ex- 
haust steam was respectfully given its true 
monetary value after that occasion, and the 
old slide-valve engines held sway as long as 
there was abundant use for the discharge of 
their exhaust. 

This illustration demonstrates the im- 
portance of providing a heating system that 
will make efficient use of exhaust steam, since 
each pound so used reduces the otherwise 
necessary boiler steam by nearly a like 
amount. In fact, cases have been reported 
where more fuel was required to heat a plant 
with the engines shut down than with the en- 
gines running under full load while heating 
the building with their exhaust steam. This 
may be explained (in case pressure is used) 
by a consequent increase in the heat dis- 
charged by the radiators, as will be later 
discussed. Under these circumstances, as far 
as fuel is concerned, the power obtained is 
a pure by-product of the operation of heat- 
ing. 

Heating efficiency is defined by the same 



158 PREVENTING POWER-PLANT LOSSES 

formula as that used in boiler and engine 
testing. It is output divided by or compared 
to input. The input is the total heat in the 
steam delivered to the system, and the out- 
put is the heat which is usefully applied. 

For illustration, let us examine the case 
of a single radiator which receives steam at 
1.3 pounds above atmospheric pressure, all 
the steam being condensed in the radiator, 
which discharges its water at atmospheric 
pressure and at a temperature of 211 de- 
grees. We then have the following figures: 

Input per pound of steam 1,152 B.t.u. 1 

Discharge per pound of steam 179 B.t.u. 

Useful output, or radiation per pound of 

steam 973 B.t.u. 

Efficiency = Output + Input = 973 h- 1,152 
— 84.4 per cent. 

Thus 84.4 per cent of the total heat in the 
steam has been converted into useful radia- 
tion. The drip contains the balance, that is, 
15.6 per cent of the original input. Now if 
this drip could be returned to the boiler with- 
out loss of temperature, as compared to feed- 
ing the boiler with water at 32 degrees, we 
should reduce the coal bill about 15.6 per cent. 
In this event, should we credit to the heat- 
ing system the heat made useful by its return 
to the boiler, our over-all heating efficiency 

1 These heat values are measured from 32 degrees F. 



THE HEATING SYSTEM 159 

would approximate 100 per cent, barring 
losses in steam and drip piping. 

This illustrates maximum heating efficiency 
for low-pressure systems operating on close 
to atmospheric pressure. Such a system is 
highly effective for exhaust-steam heating, 
since the horse-power and steam consump- 
tion of the engine are not materially affected 
by this low back-pressure. 

If it were practicable to hold the hot water 
of condensation in the radiator until its tem- 
perature was further reduced the efficiency 
of the radiator would be increased. On the 
other hand, the heat in the returns to the 
boiler would be correspondingly reduced. 

It is almost needless to state that all hot 
drips from a heating system should be re- 
turned to the boiler. The foregoing exam- 
ple illustrates the effect on the coal bill of 
returning the drips when all the boiler steam 
is directly applied for heating purposes. // 
only a fraction of the total live steam pro- 
duced is used for heating, then the fuel sav- 
ing effected will be proportionally reduced. 
Thus in the above case, if a condensing en- 
gine required one-half of the boiler steam, 
then the returns of all the drips of the heat- 
ing system would amount to only 7.8 per 
cent, instead of 15.6 per cent, of the heat in 



160 PREVENTING POWER-PLANT LOSSES 

the original boiler steam, and a correspond- 
ing part of the coal. 

The element of time enters importantly 
into snch calculations. Thus in this last case, 
if heating is discontinued in the warm 
months, the return of the drips will affect the 
yearly coal consumption to a still less degree, 
and computations of savings must be made to 
suit the exact conditions of operation apply- 
ing to the case under consideration. 

A common error among plant owners is to 
ascribe undue economy to the heat that may 
be carried in water resulting from the con- 
densation of steam. They conversely greatly 
under-estimate the heat carried in exhaust 
steam. As a matter of fact the heat in a 
pound of water at 212 degrees is only 180 
British thermal units reckoned above the 
freeezing point ; whereas in a pound of steam 
at the same temperature the heat units num- 
ber 1,150. Hence if this steam is condensed 
in a radiator it gives out 970 heat units, and 
the drip will contain 180 heat units. Never- 
theless I have found the management very 
anxious about correcting the loss due to a few 
escaping drips, while at the same time large 
quantities of uncondensed exhaust steam 
were blowing away almost unnoticed. Pound 
for pound, the waste which attracted the 
manager's attention was equal to less than 



THE HEATING SYSTEM 161 

one-fifth of the heat being carried away in 
the disregarded exhaust steam. 

This is a good thing to remember, and it 
will stand twice telling: — Utilization of the 
exhaust steam saves five times as much coal 
as the return of an equal weight of hot drips 
to the boiler. 

I do not intend to reduce the proper em- 
phasis on the value of conserving hot drips, 
but I do desire to present the various phases 
of the power problem in their true relation 
to each other ; for only in the light of such an 
understanding will industrial power users 
eventually be enabled to place their plants 
on a basis of high economy. 

The efficiency of radiating surface is quite 
another thing from the efficiency of the pro- 
cess of heating. The former use is an un- 
fortunate application of the same term, and 
indicates the rate of heating rather than true 
efficiency. Thus if a radiator or heating coil 
is so constructed as to impart to the air or 
liquid say 426 B.t.u. per hour for each square 
foot of its surface, it is said to have a higher 
efficiency than one which gives out only 300 
B.t.u. per square foot. This "rate efficiency" 
is used to determine how many square feet of 
heating surface will be required to warm a 
building or to perform a given amount of 
radiation. It has therefore no fixed rela- 



162 PREVENTING POWER-PLANT LOSSES 

tion to the waste or conservation of the heat 
in the steam. 

A comparison has been made to show the 
relative heating values of high- and low-pres- 
sure steam. It was seen that steam at atmos- 
pheric pressure contains within 3% per cent 
as much heat as at 101.3-pounds pressure. 
There are, however, two factors which should 
be considered before attempting the substi- 
tution of low- for high-pressure steam. Other 
things being equal, more radiating surface is 
needed for the low-pressure steam. This is 
because the rapidity with which the heat is 
given off is proportional to the difference in 
temperatures existing between the steam in 
the radiator and the surrounding air or 
liquid. A square foot of direct heating sur- 
face will transmit to still air about 1.8 1 B.t.u. 
in an hour for each degree difference in tem- 
perature between the air and the steam when 
that difference is about 142 degrees. 

Let us see the effect that would be pro- 

1 The coefficient of radiation 1.8 increases gradually as the temperature 
difference increases. Fair values for the above example are as follows: 



Steam pressure, Gauge 


Temp. 


Temp. Air 


Temp. Diff. 


Coefficient 


pounds 


Steam 








101.3 


339 


70 


269 


2.30 


20 


259 


70 


189 


1.98 





212 


70 


142 


1.80 



For a given temperature-difference the coefficient also varies with the 
design of the radiator or heating coil . One cause of this is the interference 
of nearby pipes or sections. See Carpenter's "Heating and Ventilating 
Buildings." 



THE HEATING SYSTEM 163 

duced on the heating of a building from 
changing the pressure of steam in the radia- 
tors. Assuming the temperature of the air to 
be 70 degrees and selecting the correct co- 
efficients from the footnote, we shall find 
that a square foot of surface will radiate 
in an hour : 

255 heat units with lb. steam pressure 
374 heat units with 20 lb. steam pressure 
618 heat units with 101.3 lb. steam pressure 

From the above it would appear that with 
a given amount of radiating surface, steam 
at atmospheric pressure would give only 
about 68 per cent of the heating effect to be 
derived from steam at 20 pounds. In actual 
practice, however, I have substituted the 
lower for the higher pressure and at the 
same time increased the heating effect from 
the radiators. This apparent discrepancy 
between theory and practice may be ex- 
plained by the fact that the former system 
was poorly designed. The circulation of the 
steam was imperfect and the distribution of 
heat to the various departments of the fac- 
tory was not uniform, consequently the en- 
tire radiating surface was not effective. 

When the low-pressure exhaust steam was 
substituted certain changes were recommend- 
ed which so improved the circulation and 



164 PREVENTING POWER-PLANT LOSSES 

distribution that the entire heating surface 
became active. This change more than com- 
pensated for the former advantage of the 
higher steam pressure. 

Formerly, in this case, steam from the boil- 
ers at 125 pounds was lowered to 20 pounds 
by means of a reducing valve for the heat- 
ing system. In place of this reducing valve 
I substituted a 150 horse-power non-condens- 
ing Corliss engine, which expanded the steam 
down to atmospheric pressure before it was 
used for heating. The power thus produced 
(at least about 90 per cent of it) became a 
pure by-product of the steam heating. This 
resulted in producing an engine horse-power 
hour for about 3 pounds of steam or 0.375 
pounds of coal, a performance that cannot 
even be approached by the largest and most 
refined type of central power-station that it 
would be possible to conceive, for an ideally 
perfect engine would not even approximate 
this figure. This economy could not have 
been effected, however, without a very care- 
ful design of the exhaust system. 

The second factor referred to as demand- 
ing consideration previous to the substitution 
of low-pressure for high-pressure heating is 
the question of temperature. 

There is no limit as to the amount of heat- 
ing that can be accomplished by an adequate 



THE HEATING SYSTEM 165 

supply of exhaust or low-pressure steam, but 
since its temperature is lower than that of 
steam under pressure there is a limit as to 
the temperature obtainable by its use. For 
all ordinary heating of buildings, however, 
exhaust steam will give as high a tempera- 
ture to the air as may be desired, and cases 
of dry rooms may be quoted where a tem- 
perature of 150 to 170 degrees is maintained 
with exhaust steam. We may remind our- 
selves also that exhaust steam in a properly 
designed feed-water heater will bring the 
temperature of the water to within about 5 
degrees (or less) of its own temperature. 
For instance, with the steam at atmospheric 
pressure and having a temperature of 212 
degrees, we may expect to secure feed water 
at about 207 degrees. 

Heat cannot flow from a colder to a warmer 
body. Consequently the degree of heating 
possible is limited by the temperature of the 
steam used. Thus steam at 2.3-pounds pres- 
sure (temperature 219 degrees) could not un- 
der perfect conditions produce a tempera- 
ture of over 219 degrees in the surrounding 
air or liquid, whereas steam at 101.3-pounds 
pressure under ideal conditions would raise 
the surrounding medium to its own tempera- 
ture of 339 degrees. There are therefore cer- 
tain applications where it is necessary to 



166 PREVENTING POWER-PLANT LOSSES 

heat with high-pressure steam in order to 
obtain the higher range of temperatures. 

Before proceeding, and in close connec- 
tion with the above points, it may be well for 
some of us to clarify our minds in regard 
to the difference between temperature and 
heat. Temperature is the measure of the 
intensity, or degree of heat. The heat unit 
or B.t.u. measures the quantity. For exam- 
ple, we may have two different weights of 
water at the same temperature of, say, 200 
degrees. Although the intensity of heat is 
the same in each case, if the one mass of 
water weighs 10 pounds and the other 20 
pounds, the latter represents double the 
amount of heat of the former. Thus tem- 
perature alone is no measure of heat, any 
more than pressure is a measure of the quan- 
tity of steam generated in a boiler. 

High-pressure steam heating in the factory 
is likely to be less efficient than low-pressure 
heating when the discharge of the radiator 
is controlled by the usual steam trap. Ef- 
ficiency is here considered in the true sense. 
If the high-pressure drip is directly fed to 
the boilers by means of the return type of 
trap, then the high-pressure may be as ef- 
ficient as the low-pressure system, provid- 
ing air binding is eliminated. The objection 
to this method is that the boiler-feed water 



THE HEATING SYSTEM 167 

is introduced by two separate means (the 
return trap and the feed pump) and this in- 
terferes with its correct and convenient 
measurement for the daily records that are 
so essential to the efficient operation of the 
boiler plant. 

The object of a trap is to permit the dis- 
charge of water condensed from the steam 
and to prevent the escape of all uncondensed 
steam. An efficient trap also provides for 
the release of air from the radiator. If it 
fails in this last respect the circulation of 
the steam is blocked and a portion or all of 
the heating surface becomes ineffective. The 
make-up water supplied to the boiler con- 
tains air which is conveyed with the steam to 
the heating coils. The steam condenses and 
is discharged by the trap as water, but un- 
less special provision is made the air accu- 
mulates in the radiator until the passage or 
entrance of the steam is prevented, thus chok- 
ing the system. It is this action of badly 
designed systems that has led to the errone- 
ous belief that to secure proper heating it 
is necessary to use pressure and to "blow" 
steam through the radiator uncondensed. 
Each pound of steam blown out in this man-' 
ner represents a loss of 100 per cent of its 
available heating value, hence the wasteful- 
ness of this useless procedure. Of course its 



168 PREVENTING POWER-PLANT LOSSES 

practice does result in driving the air out 
of the system, but it does so at the expense 
of an excessively heavy consumption of 
steam and fuel, and it is quite unnecessary 
if the heating plant is correctly laid out and 
specified. 

The reason why heating with steam at a 
higher pressure is less efficient than with 
steam at atmospheric pressure (or there- 
about) is that in the former case a consider- 
able quantity of uncondensed steam is 
discharged with the water of condensation. 
This statement applies to heating systems 
equipped with the usual types of bucket or 
float traps which allow the drips to return 
to a vented hot well or receiver from which 
they are pumped back to the boilers. 

Even assuming that such a trap is in per- 
fect working order this blowing out of live 
steam will occur. The water which accumu- 
lates in the trap has about the same tempera- 
ture as the steam in the radiator to which 
it is connected. Assume for example that 
the steam has a pressure of 20 pounds. Its 
temperature will be about 259 degrees and 
the water discharged by the trap will have 
nearly the same temperature. Hence w T hen 
it discharges to atmospheric pressure it will 
give off steam until it is cooled down to 212 
degrees. In this case the amount of steam 



THE HEATING SYSTEM 169 

" blown off" will be equivalent to 57 * heat 
units, or about 5 per cent of the total heat in 
the steam supplied to the radiator. The ac- 
tual weight of water evaporated is also ap- 
proximately 5 per cent of the weight of the 
original steam. This re- evaporated steam 
finds relief through the first vent pipe that 
may be provided, and is therefore wasted. 

In addition to this item an added and more 
serious loss occurs with high-pressure steam 
heating. This is the discharge of live steam 
through the trap which accompanies the 
water of condensation, and it is due to the 
inefficiency of the trap itself. I have found 
traps blowing through so much steam in this 
manner that the waste from this cause 
amounted to approximately as much heat as 
was required to heat the buildings. This 
was due principally to bad design of the 
traps, and partially perhaps to the worn con- 
dition of their mechanism. 

The higher the steam pressure the greater 

1 Calculation of loss by re-evaporation: — 
One pound steam at 20-pounds pressure contains 1,167 B.t.u. above 32 deg. 

One pound water at 259 degrees contains 228 B.t.u. above 32 deg. 

One pound water at 212 degrees contains 180 B.t.u. above 32 deg. 

One pound steam at 212 degrees contains 1,150 B.t.u. above 32 deg. 

Let x = weight of water evaporated into steam at 212 degrees. 

Then 1 — x — weight of remaining water at 212 degrees. 
1,150 x 4- 180 (1 — x) == 228 and 
x = 0.0495 pounds steam at 212 degrees. 

Hence waste is 0.0495 X 1,150 = 57 B.t.u. per pound of steam fed to 
radiator. 

This is 57 s- 1,167, or about 0.049 of the heat in the steam supplied. 



170 PREVENTING POWER-PLANT LOSSES 

will be the losses caused by re-evaporation 
in the discharge and by the direct " blowing 
through" of uncondensed live steam. 

A low-pressure system of heating is there- 
fore more likely to be economical, entirely 
aside from the question of exhaust steam. 
But it is necessary to point out at this junc- 
ture that the economy of low-pressure heat- 
ing is not effected at the boiler. I have found 
superintendents and managers who had an 
idea that if they could change a boiler from 
high- to low-pressure they would produce a 
direct saving in fuel. Let us remember, as 
before stated, that it requires within 3% per 
cent as much heat to make steam at pounds 
gauge pressure as at 101.3 pounds, and the 
fuel required in either case is very closely 
proportional to these values. To be strictly 
accurate, the boiler operating at the lower 
pressure would have a lower temperature, 
so that there would be about 127 degrees 
greater difference between the boiler and fur- 
nace temperatures, which would tend toward 
a slightly better absorption of heat from the 
fire. The actual effect, however, would be a 
very small gain indeed and, practically 
speaking, insignificant. 

There is one other point in regard to pres- 
sure which deserves emphasis. In many old- 
fashioned live-steam heating systems a high 



THE HEATING SYSTEM 171 

pressure is used where a lower pressure 
would do the work. In such old systems the 
traps are likely to be poor and badly ar- 
ranged, or there may be a conspicuous ab- 
sence of traps at many points. In these an-, 
tiquated plants there is much "blowing 
through ' ' of the steam. It is obvious, there- 
fore, that if the initial pressure be made as 
low as possible the steam waste will be re- 
duced accordingly, for the discharge of a 
pipe is proportional to the pressure. There- 
fore a crude but paying improvement under 
these rough conditions is the installation of 
a pressure-reducing valve between the boiler 
and the heating system. Or if no engines or 
pumps are operated the boilers themselves 
may be run at the reduced pressure if the 
steam mains are of sufficient capacity. 

A very common trouble discovered in heat- 
ing systems is ineffective circulation of the 
steam chargeable to badly designed drip 
lines from the radiators or soils. The water 
of condensation should be conveyed back to 
the boiler room by branch and main pipes 
of adequate capacity. These drip pipes 
should have a gradual slope toward the boiler 
plant so that the water will flow by gravity 
throughout. If there is depression in the 
line a "pocketing" will occur, drainage will 
be incomplete, and the capacity of the re- 



172 PREVENTING POWER-PLANT LOSSES 

turn will be reduced. The gross effect is the 
choking of the circulation, necessitating the 
use of pressure for its re-establishment, and 
this often results in the otherwise unneces- 
sary use of live steam. 

Sufficient reference has been made to the 
re-evaporation or discharge from the radi- 
ators of a part of the drips as steam to per- 
mit realization of the fact that the return 
lines must be designed to carry not only 
water but steam as well. Consequently am- 
ple capacity of these pipe lines is an essential 
feature to efficiency of heating operation. 

This discussion on the broad principles of 
heating is merely by way of introduction to 
our investigation of this department of the 
factory power-plant problem. We must here 
remind ourselves that our " steam doctor' ' 
has obtained the individual efficiencies of the 
boiler and engine plants and is equipped with 
full data on their everyday working perform- 
ance. The heating problem is therefore at- 
tacked in the full light of its relations to the 
steam-making and steam-consuming equip- 
ment. The specific question next in line is 
as follows: — 

What are the heating requirements of the 
plant under examination? There are several 
methods of obtaining this information, but 
they may be classed under two heads : — 



THE HEATING SYSTEM 173 

(A) By actual tests under working condi- 
tions, this being the more satisfactory way. 

(B) By calculation from accurate data 
pertaining to the particular case in hand. 
This is the method in general use by design- 
ing engineers, since the first scheme is of 
course impracticable before the plant is in 
operation. 

(A) As we are considering a working fac- 
tory we shall apply the first method wher- 
ever possible. Each plant presents a spe- 
cial problem as to the simplest manner of 
making these tests. During the investigation 
of the boiler plant an accurate water weigh- 
er or measuring apparatus has been set up 
for recording the feed water. This is al- 
ways kept in readiness for use until the 
examination of the entire plant has been 
completed. 

If therefore we can isolate one or more 
boilers to supply steam exclusively for heat- 
ing, we have simply to weigh the feed water 
to such boilers in order to determine how 
much steam is consumed by the radiation. 
Temperatures and pressures are of course 
carefully observed during the heating test. 
This works out beautifully for the measure- 
ment of live-steam heating. Now by modifi- 
cation the same system can be made to re- 
cord the amount of exhaust steam supplied 



174 PREVENTING POWER-PLANT LOSSES 

to those portions of the radiation. I have 
done this in the following manner: 

The exhaust steam from the engine which 
supplied the heating system was temporarily 
turned out of doors through the relief valve. 
Then live steam from a single boiler was 
supplied through a reducing valve to take 
the place of the exhaust steam. The reduc- 
ing valve was adjusted to give the same pres- 
sure in the heating system that was regular- 
ly maintained with the exhaust steam, thus 
duplicating the heating conditions. The 
water evaporated in the test boiler was re- 
corded by the automatic weigher and thus 
the exhaust or low-pressure heating require- 
ments were accurately determined. 

Now since the steam consumption, and 
therefore the exhaust steam per horse-power 
hour of the engine, had already been deter- 
mined, it was only necessary to take indica- 
tor cards during the heating test. From the 
engine horse-power hours the exhaust steam 
produced was readily computed. From the 
efficiency of the engine correct allowance 
(about 6 per cent in this case) was made 
to give the true heating value to the exhaust. 
It was now known exactly how much heating 
was required, how much was available in the 
form of exhaust from the engine, and con- 
sequently how much was wasted through the 



THE HEATING SYSTEM 175 

relief valve in everyday practice of that sea- 
son of the year. 

These tests were made to discover whether 
it would pay to install a more efficient type 
of steam engine. It was found, however, 
that since over 90 per cent of the exhaust 
steam was utilized, an improved type of en- 
gine would not pay for the interest on the 
money required for its purchase. This re- 
sult necessarily included a consideration of 
the fuel cost of steam in the boiler plant. If 
the latter had been sufficiently high a better 
engine would have paid for itself. 

This shows how absolutely all phases of the 
power-plant problem are bound up together, 
and all must receive due consideration unless 
common guesswork is to be relied upon. 

Another method of making an actual de- 
termination of heating demand is to catch 
and weigh the hot drips from the radiation. 
If the object is to learn the total amount of 
steam consumption it is necessary to con- 
dense the steam which accompanies the ac- 
tual water of condensation, in order to obtain 
the full weight of steam fed to the heating 
system. 

One way to accomplish this is to allow the 
drips to enter a coil of pipe submerged in 
cold water, thus forming a condenser, and 
then to weigh the resulting water at the cold 



176 PREVENTING POWER-PLANT LOSSES 

end. During the test (which should extend 
preferably over a complete run of the plant) 
full observations should be taken of the tem- 
peratures of the air in the work rooms, the 
dry rooms, etc., as well as out of doors; a 
recording gauge should be used or periodi- 
cal readings of steam pressure taken, both 
at the boiler and of the steam entering the 
heating system; and systematic readings of 
the condensation should be taken and regu- 
larly recorded. 

Where the flow of steam to a heating sys- 
tem is nearly constant and is without pulsa- 
tions (as in the case of engine exhaust) the 
heating steam may be measured by attaching 
to the supply pipe a special form of steam 
meter. Some of these depend upon the prin- 
ciple of the Pitot tube and others employ 
the Venturi meter system. So much for ac- 
tual tests under working conditions. 

(B) Now supposing, under the circum- 
stances that often occur, it is impracticable 
to make such trials as we have just de- 
scribed ; we have yet a means to arrive at an 
approximation of the heating demand by 
process of computation from data. 

Such method may for instance be necessary 
in the winter time to determine the summer 
heating load, or vice versa, and as previously 
stated this system is used principally by ar- 



THE HEATING SYSTEM 177 

chitects and heating engineers in the design 
of new buildings. The amount of heat that 
is required to keep a room or building 
warmed to a given temperature depends 
upon two factors: 

1. The loss of heat carried away by the 
warm air constantly escaping to make room 
for the fresh air admitted for ventilating 
purposes. With this is included the acci- 
dental escape of warm air through leaks 
around doors and windows, and its diffusion 
through walls. 

2. The loss of heat by radiation through 
walls and closed doors and windows. 

The amount of heat required to overcome 
the first loss depends upon the rapidity of 
air changes allowed in the room and upon 
the temperatures of the air in the room and 
the air outside. 

Authorities compute that each adult per- 
son in a room requires at least 30 cubic feet 
of fresh air per minute to maintain a fair 
standard of purity. Hence the air changes 
required per hour primarily depend upon 
the number of workmen in the shop, together 
with its cubical contents. If the rooms are 
large and the workmen few, the necessary 
air changes per hour are lessened, so that 
this figure depends for its determination 



178 PREVENTING POWER-PLANT LOSSES 

upon local conditions. 1 Mr. J. Byers Hol- 
brook allows "one change of air per hour 
for the average type of city building", in- 
creasing this allowance for corridors and 
first floors. Other engineers designate vari- 
ously from a fraction of one change to as 
high as three changes per hour for different 
sets of conditions. 

In addition to ordinary ventilation special 
problems arise, such as the supply of air for 
process work in dry rooms, etc. In such 
cases decisions based upon experimental 
data are the most reliable. 

Having once decided upon the rate of ven- 
tilation it becomes a simple matter to com- 
pute the heat or steam required, and conse- 
quently also the amount of radiating sur- 



1 Example: — A room contains 1,000 cubic feet of air. The minimum 
outside temperature is degree F. Temperature to be maintained in the 
room is 70 degrees. Air changes per hour allowed = 2. 

1 cubic foot of air at 70 degrees weighs about 0.0745 pounds. 

Specific heat of air is 0.2375. 

Hence 1 B.t.u. will raise the temperature of 56.5 cubic feet of air 1 degree F. 

The problem is to raise 2,000 cubic feet of air per hour 70 degrees F. 

2,000 X70 

= 2,480 B.t.u. per hour required to warm the air for ventilation. 

56.5 ' 

Then the amount of steam needed at atmospheric pressure will be 

2,480 

= 2.56 pounds steam per hour. Figuring the "rate efficiency" of 

the radiators at 1.8 B.t.u. per hour per degree difference per square foot and 
steam at 212 degrees the temperature difference will be 212 — 70 degrees 
= 142 degrees, and 1.8 X 142 degrees = 255.6 B.t.u. per hour per square 
foot of surface. 

2,480 
Therefore the amount of radiation required will be = 9.7 square 

feet, which will warm the air for ventilation. 



THE HEATING SYSTEM 179 

face that must be provided and installed on 
this account. 

Now in addition to the requirement of 
warming the ventilating air we must provide 
for the second item, that is, the heat need- 
ed to overcome the loss by radiation through 
walls and windows. Of course the heat loss 
through a wall depends upon its thickness 
and its material. Holbrook uses 0.25 B.t.u. 
per square foot per degree difference in tem- 
perature for the average city-building wall, 
and states this coefficient will vary for brick 
walls (from 4 inches to 18 inches in thick- 
ness) from 0.24 B.t.u. to 0.68 B.t.u. The heat 
transferred by glass in windows also varies 
with conditions, but may be taken at an aver- 
age value of 1 B.t.u. per square foot of sur- 
face per hour per degree difference in tem- 
perature between the inside and outside air. 

These wall and window radiation losses 
are computed and added to the ventilation 
losses to produce the total heat and the con- 
sequent radiation required. 

For a rough and quick calculation in fac- 
tory work where the radiation is known, we 
may allow one-third of a pound of steam 
(low-pressure) consumed per hour for each 
square foot of direct radiating surface. 



Chapter VIII 
THE HEATING SYSTEM (Continued) 

'T^HUS far we have considered only direct 
■*- radiation, that is to say, cases where the 
radiator coils are surrounded by compara- 
tively still air. Now where the fan blast or 
indirect method is employed, a square foot 
of surface will give out from about three to 
six times the amount of heat transmitted by 
the same area in an ordinary radiator, de- 
pending" upon the velocity of the air and the 
temperature differences. This system sub- 
jects itself to more accurate calculation since 
it is usually more or less centralized and 
the volume of air supplied can be directly 
measured. 

Thus it is possible by actual testing and 
by computing from accurately gathered data, 
to obtain the heating requirements of any 
factory plant. 

Both the engine loads and the heating loads 
must be obtained not only for summer and 
180 



THE HEATING SYSTEM 181 

winter but for day and night as well, and 
the production of exhaust steam by pumps 
and auxiliaries must be taken into our calcu- 
lations. 

It is evident that these steam and heating 
conditions are continually varying, and the 
highest economy is possible only by balancing 
the production of exhaust steam to our heat- 
ing requirements for all conditions of opera- 
tion the year round. This introduces, next 
to the boiler plant, the most serious and the 
most important part of our factory fuel prob- 
lem. For a guide in its solution we may state 
the following working principles : 

1. Substitute exhaust for live-steam heat- 
ing wherever practicable. 

2. Design or modify the plant so as to 
produce sufficient exhaust steam (and no 
more) to take care of the heating require- 
ments at all times. 

3. If a surplus of exhaust steam beyond 
the heating demand is found, it can be re- 
duced : 

a. By more economical type of steam en- 
gines and pumps running non-condensing. 
. b. By operating one or more of the engines 
condensing during such time as their exhaust 
steam cannot be utilized. 

c. To care for the lighter heating load in 
warm weather, the exhaust production may 



182 PREVENTING POWER-PLANT LOSSES 

be reduced by running at a lighter load one 
of the non-condensing steam engines, or shut- 
ting it down entirely and shifting its work 
on to a main engine of high efficiency run- 
ning condensing. This is a simple matter 
in an electrically operated plant with a main 
engine of sufficient capacity. 

4. Where possible, always make the boiler 
steam do work by putting it through an en- 
gine before applying it to the heating sys- 
tem. Thus the power becomes a by-product 
of the fuel needed for heating. 

5. "Where condensing is out of the question, 
the amount of surplus exhaust may be re- 
duced by making a part of the power with 
oil, natural gas, or producer-gas engines. Or 
where sufficiently cheap electric power is 
available, it may be drawn upon up to the 
point at which exhaust steam balances heat- 
ing load. 

6. A compound condensing engine or 
bleeder type of turbine may sometimes best 
meet the combined power and heating re- 
quirements by drawing from the intermedi- 
ate stage or bleeder the exact amount of 
exhaust steam wanted at all seasons. Such 
steam has performed work in the high-pres- 
sure cylinder or stages before its applica- 
tion to the heating system and therefore this 
practice is highly economical. That portion 



THE HEATING SYSTEM 183 

of the exhaust or low-pressure steam not 
used for heating proceeds through the low- 
pressure cylinder or stages and delivers ad- 
ditional horse-power hours before its rejec- 
tion to the condenser. 

This effect of conserving the heat in the^ 
steam for a maximum output of power and 
heating combined may also be accomplished 
by operating a hot-water heating system in 
conjunction with a condensing turbine or en- 
gine. The water is heated in passing through 
a special heater placed between the prime 
mover and its condenser, the vacuum on 
which is reduced as more heat is required 
for the radiation, and vice versa. Thus in 
very warm weather when no exhaust is re- 
quired for heating, a high vacuum is car- 
ried with a consequent economy in steam con- 
sumption. In cold weather the vacuum on 
the condenser is reduced and more of the 
heat of the exhaust steam enters the water 
which is circulated through the radiation for 
warming the buildings. This plan is known 
as the vacuo hot-water system and will be 
further discussed. 

7. A non-condensing steam engine with its 
exhaust efficiently and wholly utilized, when 
properly credited with the live boiler steam 
that would otherwise be required for the 
heating load, will furnish a horse-power hour 




184 



THE HEATING SYSTEM 185 

for about % pounds of coal, whereas a large 
and refined central power-station can only 
approximate a horse-power hour for one 
pound of coal, 

8. In the use of exhaust steam, the heat- 
ing of the "boiler-feed water should be given 
first preference. 

Approximately one-seventh (1/7) of the 
steam from a boiler after it has passed 
through a simple engine will heat all its feed 
water from 60 degrees to 212 degrees. The 
balance of the steam (6/7) is available for 
other heating purposes. 

9. Conserve first the exhaust steam. Then 
look after the return of the hot drips from 
the heating system. Effective oil separation 
is essential with the latter, in order to pre- 
vent burning of the boilers. The return of 
hot drips reduces the amount of scale that 
is deposited in the boilers. 

10. Low-pressure is to be preferred above 
high-pressure steam for reasons of economy 
previously mentioned. 

With this list of generalities in mind, the 
engineer selects a method of heating which 
will best solve the problems of any particular 
situation. 

The final plans usually resolve into an 
adaptation of one or more recognized "sys- 



186 PREVENTING POWER-PLANT LOSSES 

terns ' ' which may best meet the conditions in 
hand. 

A brief description of a few of these will 
be apropos of our previous discussion. 

First, we may properly mention what is 
commonly known as the vacuum system, or 
more accurately the return-line vacuum sys- 
tem of steam heating. A typical installa- 
tion of this kind is illustrated in Fig. 11. Its 
principal features comprise the following: 

All the exhaust steam from the non-con- 
densing engines and pumps is led to a feed- 
water heater (of the open type in this case) 
after passing through a separator to remove 
the cylinder oil. The heater absorbs suffi- 
cient heat to raise the feed water to about 
210 degrees if properly designed. The large 
residue of exhaust steam then passes into a 
heating main from which pipes are branched 
off to the radiators and heating coils. 

The condensation from these is automati- 
cally released with the accumulation of air 
into the drip returns by the action of special 
"vacuum valves ", one of which is attached 
to each individual radiator or heater. The 
condensation and air pass downward through 
the return mains to a vacuum pump which 
maintains a pressure below atmosphere in 
the return lines. They are then discharged 
into an overhead tank, which is vented for 



THE HEATING SYSTEM 187 

the separation of the entrained air, so that 
the condensation alone flows back into the 
feed-water heater to mingle with whatever 
make-up water may be required to supply the 
boilers. The inflow of the make-up water is 
automatically regulated to suit the varying 
requirements of operation by means of a tank 
float-valve. 

If there is an over-abundance of exhaust 
for the supply of the radiation its escape is 
provided for by the back-pressure relief 
valve which is always a necessary part of the 
equipment. If, on the other hand, there is 
not enough exhaust to satisfy the needs of 
the heating system, an additional supply of 
live steam is automatically admitted to the 
heating main by means of the pressure-regu- 
lating valve shown on the drawing and so 
designated. 

The theory of the ' ' vacuum system ' ', which 
is so called on account of the light vacuum 
carried in the return piping, is very largely 
misunderstood. Many persons think that the 
vacuum pump ' ' sucks ' ' the steam through the 
radiators, thus causing a positive circulation, 
but this is not true. 

If water and air are removed from a radi- 
ator as rapidly as they accumulate and the 
discharge be otherwise sealed, it will act in 
the capacity of a condenser by the reduction 



188 PREVENTING POWER-PLANT LOSSES 

of the contained steam to water. The volume 
thus greatly diminished creates a partial vac- 
uum in the radiator, causing a positive in- 
flow of the steam from the mains, which 
carry a pressure approximately atmospheric. 
The function of the vacuum is to cause a dif- 
ference in pressure between the interior of 
the radiator and the drip line in order to 
permit a rapid discharge from the former of 
the water and air which are continually ac- 
cumulating. 

Without this return-line vacuum the neces- 
sary difference of pressure would be ob- 
tained by increasing the pressure of steam in 
the radiator. This however would result in 
back pressure on the engine supplying the 
exhaust steam, thus decreasing its efficiency 
and capacity and adding to its steam con- 
sumption, all of which disadvantages are 
overcome by a well designed vacuum sys- 
tem. 

There are a large number of successful 
systems of this class in the field and they 
differ principally in the design of the return- 
line vacuum valve which is attached to the 
radiator. These automatic valves may gen- 
erally be divided into two classes, though with 
some exceptions. 

One of these depends upon the principle of 
expansion and comprises the thermostatic di- 



THE HEATING SYSTEM 189 

vision. This type is shown in Fig. 12. Its 
operation depends upon the elongation and 
shortening of a member or stem which closes 
and opens the valve. When this expansion 
member is snrronnded by steam its greater 
length causes the valve to shut, preventing 
the escape of steam; but when water and air 




Fig. 12. Dunham Radiator Trap, Sectional View. 
Thermostatic Type. 



collect, their slightly lower temperature 
causes the valve to open, thus allowing their 
discharge into the return line. 

In the later designs of thermostatic valves, 
such as here illustrated, the expansion -piece 
is of special hollow construction and contains 
a volatile liquid which vaporizes and forms 
pressure under the heating influence of the 
steam. By such a device the effective force 
of opening and closing and the stroke or mo- 



190 



PREVENTING POWER-PLANT LOSSES 



tion of the valve may both be greatly magni- 
fied. It should always be carefully specified 
under what particular temperature condi- 
tions the valve is to operate. 







Fig. 13. Webster Radiator Trap. Float Type. 



The other large division of vacuum valves 
may be classed as belonging to the float type 
of steam traps (see Fig. 13). For their open- 
ing they depend upon the accumulation of 
water in their surrounding recess which ex- 
ercises the effect of buoyancy to lift the valve 
from its seat. These valves are generally 
provided with an auxiliary port for the re- 
lief of air from the radiator. A continuous 
passage of air or steam takes place through 
this port, and when there is not enough air 
to satisfy the calculated leakage, uncon- 



THE HEATING SYSTEM 191 

densed steam takes its place and passes un- 
used to the return line. 

A vacuum system may be applied equally 
well to indirect radiation or to any kind of 
steam-heating apparatus as a means to pro- 
mote efficient circulation, and to reduce back 
pressure on engines and pumps when exhaust 
steam is used. 

When both high- and low-pressure heaters 
are employed the high-pressure drips should 
not be discharged directly into the return line 
of the vacuum system, since the steam that 
will be re-evaporated in the low pressure of 
the partial vacuum interferes with the action 
of the vacuum pump to such an extent that 
a spray of cold water must be injected into 
the suction of this pump to enable it to per- 
form its function. The secondary result is 
the cooling of the otherwise hot drips, some- 
times to the extent of producing an over- 
supply of feed water with the attendant 
waste of heat to the sewer. 

It is possible, however, to use a single low- 
pressure return main for both high- and low- 
pressure heating. This is accomplished by 
allowing the high-pressure trap to discharge 
into a receiver, the top of which is connected 
to a low-pressure steam supply main. Thus 
the "blow" or steam from the high-pressure 
radiator is returned for a second use, this 




192 



THE HEATING SYSTEM 193 

time in the low-pressure system. The water 
which accumulates in the receiver is drawn 
off through the vacuum valve into the low- 
pressure return line. This scheme, which is 
shown in Fig. 14, not only eliminates a sep- 
arate high-pressure drip main, but also re- 
sults in conserving the "blow" of the high- 
pressure traps, which would otherwise be 
wasted. 

Before the invention of vacuum systems 
the gravity system was in general use. Each 
radiator was equipped with a steam-supply 
pipe and a drip line, each controlled by a 
hand valve. The main drip from several 
heaters was often led into a common trap 
of the bucket or float type. This arrange- 
ment is particularly liable to air binding, and 
the by-pass on the trap would have to be 
opened on occasion to blow out the system 
and start it working again. Various forms 
of automatic air-relief valves were applied 
to the individual radiators, which proved 
helpful in general toward the relief of air 
binding, though they also caused much 
trouble through leakage and adjustment dif- 
ficulties. Some, of course, were better than 
others. 

If the trap itself became filled with air the 
float or bucket would not work. Then the 
by-pass or air cock would have to be opened 



194 PREVENTING POWER-PLANT LOSSES 

and the system "blown out" to enable it to 
resume operation. When the steam was shut 
off on a heater without closing the drip, the 
vacuum thus caused would tend toward 
"water-logging" and "hammering". 

The next real step in advance was the ap- 
plication of the vacuum air-line system. This 
is the gravity system plus a small air pipe, 
attached to each radiator, and running into 
a main air line to which a vacuum pump or 
ejector is attached. The withdrawal of air 
from each radiator into the air line is gov- 
erned by an automatic valve leading to the 
air line, which opens on cooling and closes 
when steam attempts to pass. This scheme 
much improved the circulation, but did not 
include the automatic and regulated relief 
of water from the heaters. This last feature 
was later combined with the removal of air, 
in the vacuum return-line system first de- 
scribed. 

There are many variations and combina- 
tions of these several systems, but it is not 
our present purpose to treat of them in fur- 
ther detail. 

The question of direct or indirect steam- 
heating may be decided upon the merits of 
any special case. The latter has the advan- 
tage of a centralized use of the steam, gener- 
ally in or near the engine room, and is under 



THE HEATING SYSTEM 195 

direct control of the engineer. The usual 
indirect system employs a blast fan which 
may either induce or force the air through 
a coil or heater whose pipes or sections are 
supplied with steam, although hot water may 
be employed as the heating medium. The 
heated air is then conducted in proper flues 
and discharged as desired in the more or less 
distant work rooms. 

There is a tendency to supply more air 
with a fan-blast system than is actually 
needed ; consequently when there is no return 
air-flue provided the fan may consume a 
wasteful amount of steam. Power also is 
required to drive the fan, but the additional 
exhaust steam thus produced may often be 
consumed in the coils of the fan itself, in 
which event only an insignificant amount of 
steam or fuel for power is chargeable against 
the fan system. 

From the standpoint of operating econo- 
my (including the consideration of repairs, 
convenience, and a greatly reduced amount 
of radiation and steam piping which would 
otherwise have to be distributed throughout 
the plant) it can be readily seen that the fan- 
blast system has some marked advantages. 
The less radiating surface required is due to 
the velocity with which the air impinges upon 
it. A blast heater depending on conditions 



196 PREVENTING POWER-PLANT LOSSES 

of operation will condense from three to six 
times as much steam per square foot per 
hour as will a direct radiator in compara- 
tively still air; that is to say, the "rate effi- 
ciency" of the blast coil is very high. This 
can be nicely demonstrated by directing the 
air blast from an ordinary electric desk fan 
upon the surface of a steam radiator. I have 
seen a cold office quickly warmed by this 
means. 

A method of applying hot-water heating in 
such a manner that all the exhaust from the 
prime mover is utilized either for heating or 
producing additional power is treated in the 
writings of Ira H. Evans, who describes the 
operation of a plant so arranged under his 
supervision. 

The turbine exhaust has two branch con- 
nections to the condenser, each under sepa- 
rate control. In one branch is inserted a 
heater through which the water for the ra- 
diating system is mechanically circulated. 
By changing the vacuum a greater or less 
amount of heat is transmitted to the heater 
from the exhaust steam. When no heating 
is required a high vacuum is maintained with 
a consequently reduced steam consumption 
for power. As more heating is needed, a 
lower vacuum adjustment permits the trans- 
mission of more heat to the radiation water. 



THE HEATING SYSTEM 197 

Furthermore, as more steam for heating is 
required its quantity automatically increases 
with the reduction of vacuum on the turbine. 

There are still other methods of heating 
which the engineer has at his disposal. Air 
or water may be warmed by passing through 
an economizer type of heater arranged to 
absorb a portion of the heat which escapes 
from the uptakes of boilers. Or such heaters 
may be separately fired, as in ordinary air 
and water heaters used in small work. 

For the factory engineer a knowledge of 
all available systems and methods of heat- 
ing is, of course, essential. But unless the 
heating design rests upon the broad prin- 
ciples which we have discussed, it makes but 
little difference which system is adopted as 
far as over-all efficiency is concerned. Pri- 
marily, minimum cost of power and heating 
do not depend upon a system. I have said 
power and heating, not heating alone. For 
it is impossible to isolate one from the other 
in an investigation directed toward the at- 
tainment of efficiency. 

Success in this matter does depend first 
and last upon a thorough knowledge of all 
the working conditions in any given case, and 
the relations involved, which include a deter- 
mination of the power and heating loads for 
day and night for all seasons of the year. 



198 PREVENTING POWER-PLANT LOSSES 

These data are to be had only by means 
of a scientific investigation such as we have 
here discussed. With this kind of a report 
in hand for basic reference, we may then 
mold a plan which will provide not merely 
for individual efficiencies of the component 
parts, but for a maximum economy of the 
whole scheme of operation all the way from 
the coal pile to the return drips, together 
with a provision for future expansion in the 
path of true efficiency. 



Chapter IX 

THE HUMAN FACTOR 

/^\VER one-fourth of the factory's yearly 
^-^ coal bill is directly controlled by the 
•fireman. In New England a single fireman 
will burn $40 to $50 worth of coal a day in 
a 500 horse-power plant. That is $12,000 to 
$15,000 worth of coal a year. This man re- 
ceives from $1.75 to $2.50 per day for his 
work. Depending upon the skill with which 
Tie handles his shovel, he will waste or save 
$3,000 to $4,000 a year of his firm's good 
money. 

Even with excellent physical equipment, 
there may prevail either high efficiency or a 
waste of fuel amounting to thousands of dol- 
lars per year. In my experience the range 
of this difference in operation alone extends 
from 48 per cent efficiency to over 70 per 
cent. Thus in this extreme, about 46 per 
cent more steam could be made from the 
same amount of coal, while for the same 
199 



200 PREVENTING POWER-PLANT LOSSES 

quantity of steam 31 per cent less coal would 
be consumed. 

Hence my introductory statement is very 
conservative ; over one-fourth of your factory 
coal bill is directly controlled by your fire- 
man. 

Forty-nine managers out of fifty are quite 
ignorant as to the disposal of this fourth 
part of their coal bill. A frequent attitude 
on their part is: "We- employ 'good men' 
and we can't be losing much," and "I guess 
you will find we are doing as well as the next 
fellow. ' ' In a recent case of this kind I found 
the firm were wasting over one-quarter of 
their fuel by wrong operation alone. When 
the matter was set right, which was quickly 
done, they expressed themselves as undecid- 
ed whether to be pleased with the saving or 
to be overcome with remorse that they had 
been losing such a large sum of money an- 
nually for so long a time. 

The "good man in charge" theory of effi- 
ciency is a sad fallacy. It cannot be de- 
pended upon without additional aid in the 
boiler plant — the simple reason being that 
no matter how "good" the man may be, un- 
less he has a means of checking the efficiency 
of his plant and knows how to use it, he will 
be utterly in the dark as to the results he is 
obtaining. 



THE HUMAN FACTOR 201 

In each of the other departments of a fac- 
tory not only is a record kept of all material 
and items of expense which enter into that 
particular process, but a most careful ac- 
count is taken of the output or product which 
forms the object^ of the expense involved. 

On the other hand, most managers are con- 
tent to keep a careful account of the expense 
of operating the boiler plant but have only 
the vaguest idea of ivhat this expense pro- 
duces. It is most usual to find strict records 
kept of the amount of coal consumed but ab- 
solutely no figures of any kind to show the 
amount of steam this coal has produced. 

This represents the same type of transac- 
tion which takes place between school boys 
when they trade jack knives, "unsight and 
unseen ". The trader knows what he is giv- 
ing but there is always a delightful uncer- 
tainty as to what he will receive. 

The " old-school' ' manager handles his 
boiler plant in precisely this manner. He 
"blows in" anywhere from $5,000 to $100,000 
in good coal each year, and takes a blind 
chance as to whether one-quarter of this 
amount will produce steam or "go up the 
stack"! He places a "good man" in the 
boiler plant and keeps track of the coal con- 
sumed, but neither he nor his "good man" 
is able to say how much steam that coal pro- 



202 PREVENTING POWER-PLANT LOSSES 

duces, nor how much it ought to produce. To 
be sure they will both guess. But judging by 
the experience I have had in converting 
guesswork of this kind into positive infor- 
mation, their guess will invariably prove to 
be a bad one. 

Managers have pretty well come to the cor- 
rect conclusion that it pays to buy their coal 
carefully, and preferably on a heat unit and 
analysis basis, but only a few have learned 
the value of measuring the product as well 
as the expense of the boiler plant. 

This guessing game may have been amus- 
ing in the days of cheap coal (though a bit 
rough on the present effort toward conserva- 
tion of the resources), but in these times of 
high and increasing coal prices the sport is 
becoming expensive. It is therefore safe to 
predict that in the future it will be followed 
by only the most reckless of our captains of 
industry. 

Some managers will resent my statement 
regarding their failure to measure produc- 
tion as well as expense in connection with 
their power-plant efficiency, because they 
keep an account of the amount of coal con- 
sumed per barrel of flour or per other unit 
of factory product. To these I would answer 
that there are so many factors other than 
power-plant efficiency which enter into the 



THE HUMAN FACTOR 203 

fuel cost of a unit of the finished product, 
that a figure obtained in this manner conveys 
no information whatever regarding the true 
performance of the power plant. 

Should this for a moment be doubted, allow 
me to cite an instance of two plants which I 
visited, both of which were making the same 
product and owned by the same company. In 
the one which possessed the better power 
equipment, the fuel consumed per unit of 
production was the greater amount. But 
this factory was handicapped by a bad lay- 
out of buildings and much more heat and 
mechanical energy were demanded for its 
operation. Thus the fuel per unit of finished 
product was in no way proportional to the 
efficiency of the power plant itself. 

This simple case illustrates the futility 
attempting to accept such "over-all data" 
as in the slightest degree indicative of the 
individual performance of the power-plant 
department. 

If efficiency is to be obtained it is necessary 
to bestow individual analysis upon this one 
small factory whose raw material is coal and 
labor and whose product is power, light and 
heat. 

The average fireman works entirely in the 
dark. He only knows he must maintain the 
required steam pressure, and he is made to 



204 PREVENTING POWER-PLANT LOSSES 

fire as many boilers as he can, "to ke*ep the 
payroll down." He has long hours — twelve 
hours a day most frequently, and sometimes 
more — and he is paid a low wage with no 
hope of more for better work. I know one 
man who fired from 16 to 18 tons of coal each 
day, serving a long battery of boilers. 

The fire-room is usually very hot and badly 
ventilated and no conveniences or shower 
bath are provided. It is the rule to find only 
such appliances for safety as may be com- 
pelled by law, and these are generally inade- 
quate. 

When matters do not run smoothly our 
old-school superintendent is very likely to 
visit the fireman with added affliction in the 
form of violent language and dockage of the 
pay envelope. I have seen and heard these 
disheartening occurrences. 

The fireman is regarded by such a man as 
but little better than an animal or beast of 
burden. He will brag about the low wages 
in his fire-room while for every hundred dol- 
lars thus saved a thousand dollars in coal is 
being needlessly wasted, and principally 
owing to this unintelligent, not to say brutal, 
attitude of the factory superintendent him- 
self. Numerous examples and experiences 
of this kind reappear before me as I write 
and they form a most unattractive picture. 



THE HUMAN FACTOR 205 

Combustion of fuel involves highly tech- 
nical considerations. It comprises a series of 
more or less complicated chemical reactions 
which are not even yet completely understood 
by scientists who have made it their particu- 
lar study, although the knowledge of the sub- 
ject which is now available, and in practice, 
is capable of producing and does produce re- 
markably high efficiencies. In view of these 
facts, is it strange that the average factory 
power plant needlessly wastes a large part 
of the expensive coal which is annually pur- 
chased for its consumption? The principal 
facts to which I refer are : the complexity of 
the science of combustion ; the low wages and 
long hours of the fireman; the lack of en- 
couragement he receives from his superiors ; 
and the ignorance and wastefulness of the 
manager who records the expense but dis- 
regards the product of his boiler plant. 

With the exception of the fireman, I know 
of no other class of worker who is entrusted 
with the expenditure of $12,000 to $15,000 
a year of the firm's money who in the first 
place receives so little as $2 to $3 per day, 
and in the second place goes wholly un- 
checked as to the return he makes to his 
company for the amount expended. 

The trend is toward a widespread reform, 
and it is actuated by two motives. The first 



206 PREVENTING POWER-PLANT LOSSES 

motive is economy. The second motive is 
humanity. It would be pleasant to reverse 
the order of these betterment forces, and at 
some future time this too will be accom- 
plished. That economy and humanity travel 
hand in hand is just beginning to be recog- 
nized, and most notably so in our own United 
States. 

The firemen in our boiler plant will in the 
future be far better paid, their working hours 
will not be excessive, and the boiler rooms 
will be better ventilated. The firemen will be 
given a direct financial interest in eliminat- 
ing the preventable waste of fuel; they will 
receive specialized education to enable them 
to produce very large economies that only 
await such educational incentive. They will 
become skilled workers who will annually 
save for their companies ten and twenty 
times the increase in their wages. They will 
feel the spirit of encouragement and co-oper- 
ation from their superiors, and when they 
are taught the value of combining brain 
with brawn their future will become wider, 
brighter, and more useful. 

The future for the factory owners will 
present a radically different and better view 
than under the present backward conditions. 
It will be positively known whether one-quar- 
ter of the coal is being needlessly wasted. 



THE HUMAN FACTOR 207 

Guesswork will become a relic of the past. 
Simple but reliable boiler-room accounting 
systems will prevail, and there will be great 
wonderment as to why such a policy had not 
been adopted years and years before. 

It will be known in the manager's office 
just what evaporation the expensive coal 
should produce, and just how closely this 
standard of efficiency is being maintained. 
The fuel cost of evaporating 1,000 pounds of 
steam will be as much a matter of common 
information as the unit cost of production 
in the factory, or as profits and dividends 
at the end of the year. 

Strikes and troubles with the men in the 
boiler plant will become very unusual, for 
the men will be contented. They will share 
in the profits of saving coal on a bonus or 
similar plan so that they are one with the 
company in their interest and incentive to 
save money. 

Safety methods and appliances will be pro- 
vided in the power plants of the future and 
the economic result of all these things, simple 
changes in themselves, will be the saving of 
millions of dollars' worth of coal to increase 
the profits of our manufacturers. 

If this reform were instituted to-day, New 
England's manufacturers alone would add 
$8,000,000 to their yearly profits. This esti- 



208 PREVENTING POWER-PLANT LOSSES 

mate is conservatively based upon the annual 
factory coal bill in these States and npon the 
extent of preventable losses which I have 
found to exist in the boiler plants of our 
industrial establishments. The firemen in 
the boiler plants will some day share in the 
division as well as in the producing of these 
extra dividends. The firemen can waste or 
save this money. It is in their hands. There- 
fore the sooner this is realized by owners, 
and the sooner they offer a just share of the 
proceeds to the men ivho work with furnace 
and shovel, the sooner will these great re- 
sults be achieved. 

But these large and worth-while economies 
can be successfully gained only by means of 
careful and intelligent application of system 
based upon scientific knowledge. It will not 
be sufficient to arrange with the firemen that 
they shall receive, say, a quarter of the value 
of the coal they save for the company. A 
"manufacturing plant never uses the same 
quantity of steam for two successive months 
or years. This constantly varies with the 
weather, with the output of the factory, with 
changes of machinery or process, with in- 
crease or decrease of the business, and with 
other conditions. Consequently so crude a 
scheme would be sure to fail. 

But it is possible to place the boiler plant 



THE HUMAN FACTOR 209 

on a productive basis in the same way in 
which other departments of any progressive 
manufacturing establishment are now han- 
dled. Measure the expense and the product, 
and get the unit cost of production. Weigh 
the coal and the water and get the evapora- 
tion per pound of coal. 

It is true that there are certain variable 
factors influencing the standards of evapora- 
tion in different plants. But it is quite prac- 
ticable to set an efficiency standard of evap- 
oration for any given plant which shall in- 
clude all -of these factors, and this is already 
being done. Thus for any individual plant 
an evaporation standard may be set which 
shall take into accurate account the average 
steam pressure, feed temperature, and heat- 
ing value and moisture of the coal as well 
as the type and design of boiler and furnace 
equipment. 

Thus in setting the evaporation standard 
recently for three different mills using the 
same coal, for which all of the above factors 
were computed into the final results, I found 
two of the mills to require a standard of 8.8 
pounds of water per pound of coal while the 
standard of the third was 8.3 pounds. At 
these standards all three plants would oper- 
ate at exactly the same boiler and furnace 
efficiency to make the weekly bonus payable, 



210 PREVENTING POWER-PLANT LOSSES 

but a lower evaporation was required of the 
third because it had no feed-water econo- 
mizer to assist toward the increase of the 
over-all efficiency. Thus equal efforts of the 
firemen themselves were equally rewarded 
quite independently of unequal plant equip- 
ments. 

A very heavy loss of fuel today exists in 
a great many of our plants which is directly 
chargeable to running too many boilers. That 
is to say, the boilers are worked very much 
below their proper rated capacity. It is a 
common failure of managers, and some oper- 
ating engineers as well, to run their boilers 
at about half their normal load. They feel 
it is " easier" to make steam if they have 
plenty of boilers on the line, but they disre- 
gard the effect on the coal bill. 

Ordinarily a boiler gives the highest effi- 
ciency when operated at or above its normal 
rating, and one reason for this is that its 
grate surface is designed for the full horse- 
power output. Consequently when too many 
boilers are under steam and they are being 
run at say one-half their rating (a most com- 
mon practice) there will be in use twice the 
grate area necessary for the proper air sup- 
ply for the coal. With this condition, there- 
fore, it is usual to find from 200 to 400 per 
cent of surplus air passing through the 



THE HUMAN FACTOR 211 

grates, to the very serious detriment of 
economy. 

One reason why this bad practice is so 
prevalent is that no one knows how much 
horse power is being developed. With a 
simple boiler-room accounting system it will 
be known just what the boilers are doing and 
consequently how many of the boilers should 
be steaming, and large economies may be 
looked for from the simple correction of this 
trouble. 

The human factor may be strikingly illus- 
trated in this connection. I have known a 
factory superintendent peremptorily to order 
the engineer to fire a certain number of boil- 
ers, although he had no information what- 
ever to prompt him as to the right number 
of boilers for efficient operation. A mistake 
of this kind alone will in many plants easily 
make a difference of one-fourth of the coal 
bill. A little intelligent reading of a suitable 
boiler meter prevents the waste chargeable 
to such an error. 

We have thus far principally considered 
the boilers and the firemen because, as pre- 
viously indicated, the greatest preventable 
waste usually occurs in this department. 

The chief engineer should always be in 
charge of, and responsible for, the entire 
power plant and the equipment, including 



212 PREVENTING POWER-PLANT LOSSES 

the boilers as well as the engines, generators, 
pumps,. etc. In some plants this concentra- 
tion of responsibility is not practised, and the 
tire-room, if managed at all, reports sepa- 
rately to the factory superintendent. This 
method or lack of method is wrong and waste- 
ful. 

If the chief engineer is properly equipped 
for his duties his first interest will be the 
efficient operation of his boiler plant. I must 
once more emphasize the important fact that 
the boiler plant offers a wider field for the 
practice of economy than the engine plant. 
This is universally true for any given plant 
where change of equipment is not considered. 

From close contact with a great many fire- 
men, both in and out of the boiler house, I 
have learned that they regard their positions 
merely as a step toward becoming operating 
engineers. They desire to get out of the 
boiler room just as quickly as possible. And 
who can blame them under the present usual 
order of things, which teaches them that fir- 
ing is only shoveling coal and working in a 
hot dirty place for low wages, and has no 
"future" for them? 

From these men brought up in this en- 
vironment, the chief engineers are produced. 
No wonder they feel like keeping out of the 
fire-room when once they are advanced to 



THE HUMAN FACTOR 213 

the engine room ! And they do ! That is, the 
majority do, and so the coal bill goes merrily 
on as big as ever. Here, then, is another 
hnman factor. The strong tendency is for 
the chief engineer to disregard the efficiency 
of his boilers becanse while still a fireman 
he was never taught the economy of skillful 
firing, or if by chance he did obtain a vague 
idea of the amount of coal he could thus 
save, he learned at the same time that it 
didn't pay to take the trouble. No records 
were kept which would enable the firm to 
know the value of a good fireman. Therefore 
it did not pay to be one. Most of us would 
feel the same way about it. This state of 
affairs is typical of factory power plants 
today. 

It is easy to understand why the chief 
engineer does not try to produce better effi- 
ciency in the fire room. There are always 
of course some exceptions, but even so the 
work of producing efficiency is extremely dif- 
ficult without such systematic boiler-room 
records as have already been briefly outlined. 

The chief engineer may take a great pride 
in keeping up his engines and steam machin- 
ery. In fact he usually does. He has gone 
into this business because he happens to be 
of a mechanical turn of mind, and he likes 
to see smooth-running mechanisms well main- 



214 PREVENTING POWER-PLANT LOSSES 

tained. He will generally be extremely care- 
ful to have the steam valves of his engines 
nicely set for the best degree of cut-off and 
compression, and he will not put up with 
leaky packings or dripping pipe joints. 

The explanation is again simple. He has 
had to learn these things in order to pass 
his engineer's license examinations. And 
this knowledge leads to economy in the engine 
room. In the fireman's license examination, 
however, the entire emphasis is placed upon 
safety. Practically no account is taken of 
the man's ability to save coal. 

These things then are self-evident. The 
fireman must desire to save coal and must be 
taught how to do it; and the chief engineer 
must be brought to realize the importance 
of his personal attention to the operation of 
the boilers and he must have adequate means 
for checking fheir efficiency. 

There is frequently an entire lack of har- 
mony between the chief engineer and his 
firemen. There is in many cases a tendency 
on the part of the chief to hold his men "un- 
der", sometimes with the idea of preventing 
them from learning enough to fill his own 
position. This is a wrong attitude and never 
leads to economy. I have found inexcusable 
wastefulness in the fire-room under such 
conditions. 



THE HUMAN FACTOR 215 

On the other hand, one of my friends in 
the operating field spends his first month in 
a new place making friends with his men and 
learning to understand them. The result is 
that in the plant of his present employers he 
has reduced the former coal consumption by 
about $40,000 per year. In the plant pre- 
vious to this one he effected a similar econ- 
omy while employing the same policy of 
friendship, co-operation, and the gradual 
education of his men. 

I have already implied the necessity of 
desire on the part of operatives ta produce 
high results, and in order to induce this de- 
sire the simplest and most direct expedient 
is to give them a proportional interest in the 
financial gains which they produce. 

But in addition to this measure, a practical 
example of which has been quoted, the factor 
of education must not be neglected if perma- 
nent results are to be achieved. 

In view of the intricacies of the science 
of combustion, it might readily be inferred 
that the education of the fireman is a difficult 
if not impossible task. But under proper in- 
struction I have seen a very ordinary fireman 
of not over average intelligence increase his 
daily evaporation from 6 pounds to 9 pounds 
of water per pound of coal. This was ac- 
complished in a week's time, and with the 



216 PREVENTING POWER-PLANT LOSSES 

aid of a very simple coal-and-water-record- 
ing system. Many persons successfully op- 
erate automobiles. And yet only an extreme- 
ly small percentage of these would be able 
to explain or even to discuss the mathematics 
or thermodynamics of the internal-combus- 
tion engine. It is the same way with the 
average fireman. It is easily possible and 
practicable to teach him to obtain and main- 
tain a good efficiency with his boilers and fur- 
naces without attempting to convert him into 
a scientific specialist. 

So far has the economy of efficient com- 
bustion come to be recognized in very recent 
years that I have heard it stated by eminent 
authorities that the fireman is becoming an 
institution of the past, and in the future it 
is well within the range of possibility that 
graduates of technical schools will operate 
the boilers of our large central stations. The 
work of firing in these great power stations 
is for the most part by mechanical means, 
and the regulation of the chemical process 
of combustion is closely guarded by the aid 
of scientific instruments, including sensitive 
draft and pressure gauges, pyrometers, and 
combustion recorders. It may therefore be 
readily comprehended in such circumstances, 
and especially where so tremendous a con- 
sumption of high-priced coal is at stake, that 



THE HUMAN FACTOR 217 

the man who understands combustion from a 
scientific standpoint may easily save his high 
salary every few days by the percentage of 
economy which his knowledge will enable him 
to effect, even if that percentage is very 
small. 

In these great centres of concentrated 
power production the mechanical equipment 
and design approach perfection to within a 
reasonable degree. But these constitute only 
one factor of the two which must ever be 
united for success in the development of effi- 
ciency. 

The other factor is operation. And this 
is purely a human factor, which unless so 
regarded will render unavailing all the sci- 
ence and expense which has entered into the 
design and installation of our elaborate mod- 
ern power plant. 

This point, which is only beginning to re- 
ceive its due recognition, cannot be over-em- 
phasized. Efficiency equals suitable equip- 
ment multiplied by operation. And since op- 
eration consists essentially and exclusively 
of the human element, we may set it down 
that Efficiency equals the product of Equip- 
ment multiplied by the Human Factor. This 
may be a new formula for efficiency, but it 
is perfectly self-evident and it has been dem- 
onstrated in practice thousands of times un- 



218 PREVENTING POWER-PLANT LOSSES 

failingly. Personally I have never investi- 
gated a factory power plant where I have not 
found that Efficiency = E x H, in which E 
equals Equipment and H equals the Human 
Factor. 

If the reader desires a further proof let 
him test the formula by process of elimina- 
tion, and before he finds a single case that 
does not perfectly conform he will be so 
exhausted with his labors that he will be 
ready to admit its value. 

It is natural that in the past when equip- 
ment was crude our attention should have 
been almost solely concentrated upon inven- 
tion and design of power apparatus. But 
mind as well as matter suffers from the effect 
of inertia. So that at the present time, when 
proportionately more can be accomplished by 
w r orking with the human factor, our minds 
by virtue of inertia alone are carried along 
the old track of invention and design and we 
are inclined to neglect the now more impor- 
tant field. 

Doubtless we shall still further improve 
our power machinery, but the margin for this 
kind of improvement is now limited, and the 
time is past due when the pendulum should 
begin to swing in the direction of the other 
element of efficiency, that is, toward the 
human factor. 



THE HUMAN FACTOR 219 

We have briefly discussed the personnel of 
the operatives, but the human factor as re- 
lated to the management, including the presi- 
dent and board of directors, counts more for 
or against efficiency than all the other ele- 
ments combined. They are the brains of the 
industry, and if they fulfill their proper 
function, they will directly control its poli- 
cies in every important phase of its activity. 
The personal ideals of the president are re- 
flected in, and permeate, every department 
of his factory. This applies to both large 
and small industries and is a matter not 
alone of theory, but of direct and close obser- 
vation. Over and over again, without fail, 
have I seen this truth demonstrated. 

If the power plant is allowed to drift along 
in a wasteful, haphazard and often dangerous 
manner this state of things is directly charge- 
able to the management " higher up." They 
alone are responsible for the operation of 
their plant and it is entirely within their con- 
trol to alter these conditions. If the presi- 
dent and his board consider the power, light 
and heating as unimportant details, these 
matters will likewise be so considered by the 
factory manager, the master mechanic, the 
chief engineer and the firemen; and this at- 
mosphere of carelessness, often unconscious- 



220 PREVENTING POWER-PLANT LOSSES 

ly created, will invariably lead to a condition 
of wastefulness and inefficiency in the power 
plant. 

In defence of the management it may be 
said that there do at times prevail such a set 
of circumstances that power-plant economy 
must be sacrificed in favor of other and more 
important considerations. 

Such a period of pressure is never a last- 
ing one, but if the trend is in this direction, 
it is advisable to make a determined effort 
to attack the power problem in the immediate 
future, otherwise operation and equipment 
will so rapidly deteriorate that only a dis- 
proportionately large expenditure of time 
and money will be able to re-establish normal 
efficiency standards. 

I cannot conscientiously close this chapter 
without at least calling the attention of my 
readers to the importance of safety in the 
power plant. This naturally is an element 
of the human factor, and to it distinctly ap- 
plies the great truth previously set down: 
that "humanity and economy travel hand in 
hand", and where the one exists the other 
will be found. 

So much has recently been said and written 
in connection with the rapidly increasing 
"Safety First' ' movement that I shall not 
attempt to duplicate any of these efforts ex- 



THE HUMAN" FACTOR 221 

cept in so far as they directly apply to the 
factory power plant. Bnt I do earnestly de- 
sire to call particular attention to the follow- 
ing matters which deserve the thoughtful ex- 
amination of all power-plant owners and 
managers. 

In case of the blowing out of a boiler tube 
or similar rupture, the steam from all the 
other boilers on the same main will rush back 
into the injured boiler and the resulting dam- 
age will be vastly magnified, with the usual 
or old-fashioned method of piping. This 
action may be prevented by the use of a non- 
return stop valve inserted on the lead be- 
tween each boiler and the steam main. This 
will automatically close and shut ofT the rup- 
tured boiler. Every plant consisting of more 
than one boiler should be equipped with this 
valve, of which a number of reliable makes 
are now available. These valves should be 
used in shutting down and " cutting in" boil- 
ers to insure their constant working condi- 
tion. 

A frequent cause of boiler explosions is 
the "cutting in" of a boiler to the steam 
main before its pressure has reached that of 
the other boilers. The non-return valve ren- 
ders this occurrence an impossibility. Con- 
sequently these appliances cannot be too 
strongly recommended. 



222 PREVENTING POWER-PLANT LOSSES 

There have been cases where a man who 
was cleaning or repairing the inside of a 
dead boiler was literally cooked to death by 
the entrance of steam from other boilers. 
This may be cansed by the failure of the 
steam valve if there is but one on the lead 
between the boiler and header. Hence two 
valves are recommended, principally as a 
good form of life insurance for the men who 
have to enter the boilers. And this should 
be sufficient reason for the recommendation 
although there are other practical operating 
advantages. 

The two-valve idea applies with almost 
equal force to the blow-off piping, and for 
the same reason, although in this case owing 
to leakage and other troubles, two valves be- 
tween each boiler and the blow-off main are 
usually provided. 

Sometimes the unfortunate man inside of 
the boiler suffers his appalling fate because 
of the carelessness of another man outside 
who, unaware of his companion's location, 
opens a steam or blow-off valve connecting 
to this boiler. The best preventive for 
such accidents consists in the use of a lock- 
ing device for both the steam and blow-off 
valves. This contrivance is simply a special 
form of wire basket which in use envelops 
the valve wheel. It is locked in position and 



THE HUMAN FACTOR 223 

the man who is to enter the boiler takes the 
key with him, thus insuring his own safety. 
These contrivances are recommended by the 
American Museum of Safety and are very 
inexpensive. It is hardly necessary to say 
that their use is recommended except on a 
steam lead which is provided with a non- 
return valve. 

Occasionally an engine, through water in 
the cylinder, may blow out its cylinder head, 
or a main steam line may burst. Either 
occurrence results in a violent strain in the 
boilers owing to the sudden drop in pressure 
and the consequent development of steam 
w'ith abnormal rapidity. Other more com- 
plicated reactions enter, and the ultimate 
result may be a boiler explosion. The pre- 
vention of this class of accident may be by 
the employment of safety stop valves; or 
by the installation of a main stop valve, hand 
operable from a safe location. The former 
is the more thorough method and accom- 
plishes its purpose by automatically shutting 
of! the boilers from the steam main when 
the sudden flow of steam causes this abnor- 
mal condition. The only objection to this 
method is that these special valves, which 
combine the two functions of stopping a sud- 
den flow of steam either out of or into a 
boiler, are more or less complicated and must 



224 PREVENTING POWER-PLANT LOSSES 

be used daily and carefully attended to -to in- 
sure a continuously fit condition. 

The second method is simpler though it 
does not cover the safety of that portion of 
the steam header which lies between this 
device and the boilers. All that is needed, 
however, is a good substantial gate valve 
whose stem is connected by chain or gearing 
in such a manner as to afford quick closing 
from the floor of the boiler room. This plan 
is illustrated in Figs. 15, 16. When an 
accident occurs of the class indicated, the 
engine-room staff are quite free to make their 
escape in the easiest manner, while a fireman 
on the safe side of the dividing wall closes 
the main stop valve without the slightest 
risk to his own person. 

Other combinations of these two general 
methods of protection are also possible and 
they may best be chosen to suit the existing 
local conditions. 

Safety Fire Doors 

One of the most common of accidents is 
the burning and blowing out of boiler tubes. 
This may result in loss of life, but a serious 
scalding at the least may be expected. The 
safeguarding of such damage is accomplished 
by the use of inward opening or safety-latch 
fire and cleaning doors. Since they with- 



8" Pipe from old Boilers 




■Wall Header 



Fig. 15. Plan op Safe Steam Piping in a Boiler Plant 



Designed by the author in accordance with the second method described on 
Page 224, Chapter IX. Each lead is fitted with a non-return valve in addition to 
a stop gate valve. The steam main has a stop valve hand-operable from the floor on 
the safe side of the wall in case of accident in the engine room. Reproduced by the 
courtesy of Power. 



msssssssmwww 



Fig. 16. Device for Operating Main Steam Valve 



THE HUMAN FACTOR 225 

stand the pressure of the escaping steam it 
is entirely confined within the boiler setting, 
and therefore finds for itself a natural and 
harmless vent through the smoke connec- 
tions. 

In many boiler rooms a source of danger 
lies in the very confined space or alley al- 
lowed at the rear of the settings. In case of 
a bursting blow-off pipe or fitting it is dim- 
cult for a man in this place to make a safe 
escape. The remedy is largely one of initial 
design. Ample passages for free exits from 
every part of a boiler room should be pro- 
vided. An alley at least four and, better yet, 
six feet wide should be planned at the rear 
of the boilers, and similar spacing should be 
made between the various batteries. 

The bach combustion arch is a point of 
danger almost universally disregarded. The 
heat at this location renders the arch a nor- 
mally weak structure. Should a man, in 
passing over, break through he would' be 
burned alive. Yet when I advised an en- 
gineer in charge to provide against this dan- 
ger by a small iron grating his answer was 
that "Nobody but a fool would walk over a 
rear combustion arch." Perhaps he was 
right, but if so I too am included in his list of 
one of the numerous classes of fools. 

Those arches belonging to the type advo- 



226 PREVENTING POWER-PLANT LOSSES 

cated by the Hartford Steam Boiler Insur- 
ance & Inspection Company are the safest 
and strongest. The brickwork is reinforced 
by cast-iron beams which are themselves pro- 
tected from the heat. In any case it is a 
simple and inexpensive matter to prevent an 
awful possibility by laying a small iron grat- 
ing bridging over the rear combustion arch. 

For the quick and safe operation of valves, 
there should be plain marks of some kind to 
indicate the nature of the piping. Some en- 
gineers resort to the simple use of markers 
or signs attached to the principal valves. 
Others adopt the more elaborate method of 
coloring the piping, employing a separate 
color for each individual class of service. 
One or the other of these systems should be 
installed in every plant wdierein the manage- 
ment places a proper value on safety and 
efficiency. In many cases it is necessary to 
get quickly to the top of the boilers when 
delay may result in damage or accident. A 
great many plants have no provision for such 
contingencies. A permanent iron ladder 
should be secured in position for quick and 
easy access to - each battery of boilers. 

In the engine room the prime requisites 
for safety are: good light and ventilation, 
careful guarding of fly-wheels, belts, pits and 



THE HUMAN FACTOR 227 

other points of danger, and the application 
of safety engine stops. 

The last alone should require further 
discussion and that may be brief. A good 
installation prevents the engine from run- 
ning away in case of accident to the governor 
or gearing. The bursting of a fly-wheel is 
often as serious in its results as a boiler 
explosion with its attendant loss of life and 
property. The safety stop is designed to 
prevent such an occurrence. 

Furthermore, should a worker become en- 
tangled in the machinery in any part of the 
factory, the engine or engines can be instant- 
ly shut down by pressing a button close by 
the location of the accident. 

There are many further details that might 
be mentioned, but it is desired to set forth 
only those special features making for safe- 
ty which though most essential are too fre- 
quently neglected. 

We may in the near future expect the en- 
actment of better boiler laws in New York 
State which shall govern both operation and 
design. These laws will compel the adoption 
of practically ail the recommendations which 
I have just made. An effort is also being 
made for the adoption of Federal laws which 
shall provide equal protection to boiler users 
in every State of the Union. This is a most 



228 PREVENTING POWER-PLANT LOSSES 

necessary measure. In some States the legis- 
lation is so absolutely inadequate to the ef- 
fectual enforcement of safety in operation 
that hundreds of boiler plants are as danger- 
ous as hidden bombs. 

The lap-riveted boiler is essentially of 
weak design and the nature of its construc- 
tion is such as to cause a constant process of 
weakening along the longitudinal seams. 
This is thoroughly understood and admitted 
by engineers, insurance companies, and de- 
signers ; and yet many such boilers are in 
use under crowded sidewalks in New York 
City today. All legislation for improved 
protection should cover the use of present 
boilers, that is to say, of old installations as 
well as new. Otherwise the present dangers 
will continue for years to come in spite of the 
new laws. 

The American Society of Mechanical En- 
gineers through a competent committee have 
prepared a preliminary report and recom- 
mendations for sound legislation for better 
boiler protection, and this should receive the 
loyal support of all users, makers and en- 
gineers. 

For the conclusion of this chapter on the 
Human Factor I may advisedly repeat that 
which I have already set down. 



THE HUMAN FACTOR 229 

Efficiency is ever the product of equipment 
and operation. 

As for equipment, while we may still look 
forward to improvement, the gain in this 
direction is bonnd to be slow, for the margin 
of betterment is now limited in view of the 
best that is already attainable. But in the 
direction of operation, the outlook offers a 
great future. Great for the factory owners 
and managers and great for the men who 
work in their poiver plants. Operation deals 
exclusively with the human element, and the 
degree of efficiency betterment which we shall 
obtain will depend upon the intelligence and 
upon the amount of love for humanity which 
we shall weave into our efforts and express 
in practical achievement. 

The pendulum has already begun to swing 
in this direction, and as it acquires accelera- 
tion we shall see more and more clearly the 
truth, which in my own limited and special 
field of work has been so forcibly brought 
home to me. 

For the operation of this law (for such I 
believe it to be), in the world-wide field of 
industry, I would sincerely recommend the 
reading of a very remarkable book which 
has proved an inspiration to so many besides 
myself. It is "The New Industrial Day", 
written by William C. Redfield, now Secre- 



230 PREVENTING POWER-PLANT LOSSES 

tary of Commerce and Labor in the United 
States cabinet. 

To return to my lesser and more contracted 
subject of Factory Power Plants, I would 
call to your final attention the fact that the 
man who works in your fire-room can save 
or lose one-quarter of your yearly coal bill. 
Your chief engineer holds additional gains 
or losses in his hands. And — well, what are 
you doing about it? 



Chapter X 

EFFICIENCY SYSTEMS FOE BOILER 
PLANTS 

TF high results are to be obtained, an 
A efficiency system must be .designed ac- 
cording to the human equipment of a plant. 

Thus in a factory where the superintendent 
is a mechanical engineer, or where the chief 
engineer is a well-educated man, a finer and 
more comprehensive system may be adopted 
than would be practicable in the case of 
"ordinary" factory conditions, where no 
one is employed who is competent to calcu- 
late even the simplest kind of power-plant 
problems. In the latter type of plant a sys- 
tem must be devised which will reduce the 
necessity for calculations to the absolute 
minimum. 

With this object in view I have standard- 
ized the efficiencies of three plants operated 
by one company in such a manner that the 
only calculation required at the end of each 
231 



232 PREVENTING POWER-PLANT LOSSES 

day is the simple division of one number by 
another. In other words, it is only necessary 
to obtain the actual weight of coal consumed 
and of the water evaporated in order to 
know the efficiency of operation and whether 
or not the bonus has been earned. 

Since the evaporation per pound of coal 
by itself signifies nothing whatever as to the 
efficiency obtained, it is necessary to compute 
into the "standards of evaporation" all the 
affecting factors as they are found by careful 
investigation to exist in any given plant 
where such standards are desired. 

These other factors are: the average heat 
value per pound of dry coal, the average per- 
centage of moisture in the coal as delivered 
to the fire-room, the average temperature of 
the feed water, and the average steam pres- 
sure maintained. Of course these factors will 
vary slightly in the same plant from time to 
time, but for commercial purposes they will 
not vary sufficiently to alter the value of the 
system. If some change of coal is made or if 
a new heater for instance changes the tem- 
perature of the feed water, the standards 
given may be modified to meet these new con- 
ditions by a simple percentage factor, as will 
be noted. 

The computation and notes on the use of 
the evaporation standards for the three fac- 



BOILER EFFICIENCY SYSTEMS 233 

tory plants above mentioned are given below, 
together with the bonus system laid out for 
this case. 

COAL STANDARD 

The coal used at this plant contains an average 
of 14,300 B.t.u. per dry lb. (Coal in test contained 
14,392 B.t.u. and 6.33 per cent moisture.) 

Moisture assumed to average 6 per cent. 

Then the net heating value of the average coal will 
be obtained as follows: 

Total heat in a pound by deducting the 

moisture— 94 per cent (14,300 B.t.u.) 13,442 B.t.u. 
Heat consumed by evaporation of 0.06 

lb. moisture and raising same from 

72 degrees to a flue temperature of 

452 degrees = 0.06 [(212—72) + 

970 + 0.48 (452 — 212)] = 74 B.t.u. 



Net available B.t.u. per lb. of coal 

weighed in fire-room 13,368 B.t.u. 



EFFICIENCY STANDARD 

With your equipment a fair standard of efficiency 
with proper handling of fires would lie between 65 
and 71 per cent. This lower mark is readily obtain- 
able without great effort, and its maintenance will 
result in a large saving over the present mode of 
operation. In accepting this standard it is to be 
noted that when the boiler test was made, No. 1 
mill came within one point of the standard, although 
the day before I found the same boilers being oper- 
ated at about 50 per cent efficiency. Raising the 
efficiency from 50 per cent to 65 per cent means a 

saving of - — -^- — - = 23 per cent of fuel. 



234 PREVENTING POWER-PLANT LOSSES 

I therefore recommend 65 per cent as the standard 
of efficiency at all three mills, although I believe this 
mark will be passed after practice with the account- 
ing system. 

I have converted this standard into a figure of 
actual evaporation per pound of coal made separately 
for each plant. This will eliminate all computation 
with the exception of dividing the water by the coal 
at the end of each day. 



COMPUTATION OF EVAPORATION STANDARDS 

Mill No. 1 



The standard for this plant is based on the feed 
water from the economizer entering the boilers at an 
average of 230 degrees. 

A change of 10 to 11 degrees in the entering feed 
water affects the standard 1 per cent. Thus if the 
feed water, by improving the arrangement of the 
feed-water heaters at this plant, should become 250 
degrees instead of 230 degrees, it would be right to 
raise the standard of evaporation by 2 per cent. 

However, with 230 degrees and 100 lb. boiler pres- 
sure, the factor of evaporation for this plant is 1.02. 

The efficiency standard of 65 per cent therefore 
calls for an actual evaporation of 8.78 lb. of water 
per lb. of coal as weighed in the fire-room, deduced 
as follows: 

A ce Actual evaporation X 1.02 X 970 

°- 65 13^68 

0.65= Actual evaporation X . 074 

ff~07l = Actual evaporation = 8 . 78 

Hence we have the standard of evaporation for No. 1 
mill, 8.8 lb. 

This is found simply by dividing the actual water 
by the actual coal consumed. 



BOILER EFFICIENCY SYSTEMS 235 

All the other factors have been taken care of in 
the setting of this standard. 

For your convenience, however, should a change 
occur in the average temperature of your feed water, 
simply add or subtract one per cent to the evapora- 
tion standard for each 10 degrees change in the feed 
water. 

Mill No. 2 

The evaporation standard for this plant is based 
on 100 lb. steam pressure and 179 degrees feed- water 
temperature. Its calculation and value are given 
below. 

Actual evaporation X 1.0737 X 970 . c _ 

L%368 = ° 65 

Actual evaporation X . 078 = . 65 

' Q = Actual evaporation =8.33 lb. 
U.U7o 

Mill No. 3 



The standard for this plant is based on the same 
steam pressure and feed-water temperature as at 
plant No. 1. That is, 100 lb. pressure and 230 
degrees feed-water temperature. 

The actual evaporation standard is therefore 8.8 lb. 

When the feed thermometers recommended are 
attached the temperature of the water entering the 
boilers can be ascertained; and, as before directed, a 
change in the evaporation standard of one per cent 
for each 10 degrees difference in the feed water should 
be made. That is, the evaporation standard should 
be increased one per cent for each 10 degrees rise in 
the average feed temperature, and vice versa. 

EFFICIENCY SYSTEM FOR THE BOILER PLANTS 

Bonus 

For each week during which the evaporation stand- 
ard of 65 per cent is maintained I would recommend 



236 PREVENTING POWER-PLANT LOSSES 

that — : dollars be added to the wages of the 

firemen of such plant. 

Standards for Earning of Bonus 

To earn this bonus the actual evaporation must be 
equal to the following: 

At Mill No. 1 — 8.8 lb. = Actual water -r actual coal. 
At Mill No. 2 — 8.331b. = Actual water -f- actual coal. 
At Mill No. 3 — 8.8 lb. = Actual water -f- actual coal. 

In order to encourage still further improvement, I 
would further recommend that for those weeks when 
70 per cent efficiency is maintained the fireman of 

that plant receive a bonus of dollars per week. 

To earn this extra bonus the actual evaporation must 
be equal to the following 

Standards for Extra Bonus 

At Mill No. 1 — 9.47 lb. = Actual water -f- actual coal. 
At Mill No. 2—8.97 lb. = Actual water ^ actual coal. 
At Mill No. 3 — 9.47 lb. = Actual water -r- actual coal. 

As before stated, the three plants are averaging 
far below the 65 per cent standards at the present 
time, and the company will save a very considerable 
amount of coal yearly by holding to the above stand- 
ards. (See other sections of this report.) 

On a conservative estimate based upon your 
present low efficiencies and large coal consumption 
you will save ten times the bonuses paid to your fire- 
men for the maintenance of the 65 per cent efficiency 
standards. 



Consider now the case of a factory in New 
England where the management of the power 
plant was under the supervision of a mechan- 



























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BOILER EFFICIENCY SYSTEMS 237 

ical superintendent, a technically trained en- 
gineer. It was possible here to install what 
might be termed a direct-acting efficiency sys- 
tem. Here the management determines for 
itself the variable factors entering into the 
computation, and then by means of a curve 
(illustrated in Fig. 17, inserted facing this 
page) determines the efficiency of the boilers 
and furnaces. 

This system entails a little work of calcu- 
lation, which, however, becomes easy as it 
is performed regularly at the end of each 
day or week, and when a slide rule is used 
can be done in three minutes' time. This 
method is more accurate than the one first 
described, since all variations in the feed 
temperature, the steam pressure, and the 
heat value and moisture of the coal enter 
immediately into the calculation of the effi- 
ciency instead of being used as a combined 
average factor as' is the case when a * ' stand- 
ard evaporation" is set. In other words, 
with the system now under discussion the 
man in charge must work out and apply the 
factor of evaporation, keep a check on the- 
heat value and moisture in the coal received, 
and apply the resulting data to the efficiency 
curve. 

With this more technical method thermal 
efficiency itself is the standard, and for the 



EFFICIENCY CHART 
4 Example: Evap. from & at 212 Degrees = 10.1 Lb. t 
B.t.u. in Coal = 14,000 
Efficiency = 70 Per cent 



B.t.u. per Lb. Dry Coal 
Fig. 17. Efficiency Chabt 



238 PREVENTING POWER-PLANT LOSSES 

plant in hand an efficiency was set which 
several boiler tests proved to be readily ob- 
tainable under actual conditions of operation 
and equipment. 

For weighing the water fed to the boilers 
a Venturi meter was installed and the coal is 
weighed as it enters the fire-room in hand 
cars which run over a track scale. Each car 
holds 1,000 to 1,500 pounds of coal. 

The result of careful checking of the work 
of the boilers has shown an improvement of 
about 20 per cent in the evaporation for the 
same consumption of fuel. 

For details of the efficiency and bonus sys- 
tem recommended at this plant I quote the 
following section of my report on this subject 
which may serve as a guide for the correct 
working out and application of such a method 
to any plant for which its use is suitable. 

It is to be noted that in setting the amount 
of bonus the amount of saving to the firm 
should be directly considered, and the under- 
lying idea should be to make the additional 
sums paid to the firemen a percentage of the 
savings produced by their increased efforts. 
Incidentally, these greater efforts relate far 
more to thoughtfulness and care than to mus- 
cular exertion. In fact, since less coal will 
be handled, the tendency is toward a reduc- 
tion of physical work. 



BOILER EFFICIENCY SYSTEMS 239 



BOILER EFFICIENCY SYSTEM 

(From Author's Report) 

1. Determine the calorific power of the average 
run of coal by sending a sample of each of several 
car loads to your chemist. 

With this figure in hand, and setting 70 per cent 
boiler and furnace efficiency as a fair standard of 
operation, you can use the table on a following 
page to determine from your coal and water records 
whether this efficiency is being maintained in the 
operation of your boiler plant. 

Thus with 14,000 B.t.u. in the coal you should get 
an equivalent evaporation of 10.1 lb. per lb. of coal, 
etc. 

2. While it is a valuable test to compare the 
separate efficiencies obtained by the different shifts 
of firemen, I would, for the sake of gaining co- 
operation among the men, bunch the results of the 
week's work and then pay a lump-sum bonus to 
be equally divided among the whole force. This 
makes each shift help the other shifts by leaving 
the fires in good condition, etc., and promotes good 
feeling. 

If any one shift or man is inefficient, the eight-hour 
records will discover the fact and they may be trained 
to better work or dropped if necessary. Under this 
system the firemen themselves will be interested to 
eliminate the inefficient men, since their bonuses are 
thereby reduced. 

Amount of Bonus 

As insurance on your coal bill, it will pay to 
spend $260 a year to keep the efficiency up to 70 per 
cent. 

In past tests I found the efficiency ranged from 
59 to 71.4 per cent, and the best efficiency (71.4 



240 PREVENTING POWER-PLANT LOSSES 

per cent) was obtained when the boilers were run at 
about normal rating and not forced, and forcing is 
unnecessary with your ample boiler capacity. 

This great difference in possible efficiencies easily 
warrants the expenditure of $260 a year for main- 
taining the 70 per cent standard. 

As the boilers were run principally under forced 
conditions, the efficiency was about 60 per cent, 
corresponding to a coal bill of $14,000 a year. By 
increasing the efficiency to 70 per cent the coal bill 
will become $12,000 a year, making a saving of 
$2,000 annually. Hence $260 a year is a very mod- 
erate amount to insure this saving which will be pro- 
duced by maintaining the efficiency standard of 70 
per cent as recommended. 

A further increase from 70 per cent to 71 per cent 
efficiency means a saving of 1-71 of the coal bill of 
$12,000 per year, that is, $169 per year. 

From 70 to 72% saves J~X 12,000 = $333 per year. 
From 70 to 73% saves — X 12,000 = $483 per year. 

to 

From 70 to 74% saves —X 12,000 = $644 per year. 
From 70 to 75% saves —X 12,000 = $800 per year. 

By allowing one-third of these additional savings 
over those produced by maintaining the 70 per cent 
standard to be paid the firemen in weekly amounts, 
the table of Bonu ; Rates on the following page can 
be used for payment. Thus when the firemen receive 
an increase of $1 the firm receives $2 in coal saved. 
No bonus is paid under 70 per cent standard, the at- 
tainment of which brings $5 a week to the firemen 
with a corresponding profit to the firm. The bonus 
for efficiencies above 70 per cent is given in the table. 



BOILER EFFICIENCY SYSTEMS 241 



EFFICIENCY STANDARDS 

B.t.u. in Coal Efficiency Evap. per lb. of 

Standard Coal from and at 
212 degrees 

13,000 70 per cent 9.39 

13,500 70 per cent 9.75 

14,000 70 per cent 10.10 

14,500 70 per cent 10.46 

(For other efficiencies use blue-print curve chart, 
Fig. 17.) 

Note: This table and curve are based on dry coal. 
If the coal contains 2 per cent moisture, add two 
points to the efficiency shown; for 3 per cent, add 
three points, etc. 

Bonus Rates 

Divide among the firemen each week the follow- 
ing sums, depending on efficiency shown by the chart 
of evaporations, and efficiency. 

Bonus 

Under 70 per cent 0.00 

70 per cent $5.00 

71 per cent 6.08 

72 per cent 7.13 

73 per cent 8. 10 

74 per cent 9.12 

75 per cent 10. 12 

Note: For determining efficiencies other than 70 
per cent use the efficiency chart on preceding page, 
(see the folding insert, Fig. 17) which eliminates cal- 
culation and saves time. 

If the efficiency as determined by any 
proper system should at any time fall below 



24:2 PREVENTING POWER-PLANT LOSSES 

the standard, the first thing to do is to have 
a calorific test and analysis made of the coal 
to determine whether the fault lies in the 
fuel. If its heat value has not become low 
enough to account for the reduction of the 
efficiency as indicated by the system, and if 
its composition does not show bad clinkering 
properties, 1 then the loss is directly charge- 
able to the operation of the boiler plant itself, 
and may be found due to bad firing, dirty 
tubes, scale in the boilers, or some matter 
directly connected with the human factor. By 
these means the efficiency of the boiler plant 
is directly controlled by the factory manage- 
ment. 

In another plant where the steam pressure 
and feed temperature are practically con- 
stant quantities, it is only necessary to set 
a standard of actual evaporation based on 
good standard coal. Since the coal used in 
this case is anthracite buckwheat, which va- 
ries principally only according to its ash con- 
tent, it is a simple and inexpensive matter to 
make frequent tests to determine its com- 
parative steaming value. This is done by 
the company's regular chemist by burning 
out the combustible from a sample and weigh- 
ing the resulting ash. The heat value of this 

1 Clinkering is caused by an ash of low fusing point, and is also asso- 
ciated with a high sulphur content in coal. 



. BOILER EFFICIENCY SYSTEMS 243 

coal is approximately proportional to the 
percentage of combustible, so that an excel- 
lent check on the calorific power of the coal 
is easily and cheaply obtained. In this way 
a good record can be kept to show the class 
of coal being purchased as it is received. 
• By the employment of this simple checking 
system, together with daily evaporation rec- 
ords from the boiler room, this plant has 
reduced its fuel cost of steam by nearly 20 
per cent. 

In still another plant where a number of 
different grades of anthracite coals were 
available at widely varying prices, and where 
conditions made it advisable to mix a certain 
percentage of soft coal with the hard, I ap- 
plied the following system after equipping 
the plant to handle these fuels. 

The object of the system was to place the 
determination and control of the commercial 
efficiency in the hands of the client, and to do 
so in a direct and simple manner which 
would entail a minimum of calculation, and 
at the same time give scope for a wide range 
of experimenting with different coal mix- 
tures and prices, with always a definite 
knowledge of the result of each trial. 

The coal was weighed in equal loads, a 
standard net weight being selected to elimi- 
nate the necessity of adding up different fig- 



TABLE I — COAL MIXTURE TABLE 

Cost per Ton of Various Mixtures 
One (1) Part of $3.50 Coal Mixed with: 



$2.25 coal = $2.39 
$1.40 coal = $1.63 
$0.90 coal = $1.19 



$2.25 coal = $2.43 
$1.40 coal = $1.70 
$0.90 coal = $1.27 



$2.25 coal = $2.50 
$1.40 coal = $1.82 
$0.90 coal = $1.42 



Find the cost of your coal mixture from this table. Then from Table II note 
your cost of evaporation. No calculating is necessary. 



table ii — Cost op fuel for 1,000 lb. of steam from and at 212 degrees 
The Results Are in Cents and Decimals of Cents 



Delivered Price of 
2,240 Lb. of Coal 


Actual Evaporations Per Lb. of Coal as Fired 
p = 40 lb. T = 190 degrees F = 1.05 


WA 


9 


m 


8 


7M 


7 


6^ 


6 


5M 


5 


4^ 


$3 . 50 


15.7 
13.4 
11.2 

10.1 
9.0 

7.8 
6.7 
5.6 
4.5 


16.5 
14.2 
11.6 
10.6 

9.5 
8.3 
7.1 
5.9 
4.7 


17.5 
15.0 
12.5 
11.3 
10.0 
8.8 
7.5 
6.3 
5.0 


18.6 
16.0 
13.3 
12.0 
10.6 
9.3 
8.0 
6.6 
5.3 


19.8 
17.0 
14.2 
12.8 
11.3 
9.9 
8.5 
7.1 
5.7 


21.2 
18.2 
15.2 
13.7 
12.1 
10.6 
9.1 
7.6 
6.1 


22.9 
19.6 
16.4 
14.7 
13.1 
11.4 
9.8 
8.2 
6.5 


24.8 
21.3 
17.7 
15.9 
14.2 
12.4 
10.6 
8.9 
7.1 


27.0 
23.2 
19.3 
17.4 
15.5 
13.5 
11.6 
9.7 
7.7 


29.8 
25.5 
21.2 
19.1 
17.0 
14.9 
12.7 
10.6 
8.5 


33 


$3 00. 


28 4 


$2 . 50 ... . 


23 6 


$2.25 


21 2 


$2.00 


18 9 


$1.75 


16 5 


$1.50 


14 2 


$1.25 

$1.00 


11.8 
9 5 







Directions: Opposite price of coal you are burning and under the actual evap- 
oration per lb. as determined by water weigher, you will find your cost for evaporat- 
ing 1,000 lb. of steam from and at 212 degrees. 

Example: Suppose you have an actual evaporation of 6 lb. of water per lb. of 
coal at $1.50 per ton. Cost of evaporation will be 10.6 cents. 

Note: With coal at $1.00 per ton you need an actual evaporation of only 4^2 
lb. to make your cost of evaporation 9.5 cents. 



244 PREVENTING POWER-PLANT LOSSES 

ures. The water was weighed in an accurate 
feed-water weigher and the result given in 
pounds. Dividing the total water by the total 
coal gave the actual evaporation. Applying 
this actual evaporation to Table IT prepared 
for their use (with their average factor of 
evaporation computed into the results), and 
co-ordinating the price per ton of coal mix- 
ture burned, they could read without compu- 
tation the fuel cost of evaporating 1,000 
pounds of water from and at 212 degrees. 

The cost of the coal mixture was also made 
available from Table I without calculation. 
Thus any amount of experimenting with coal 
mixtures and coals of different prices could 
be done and the results immediately known 
from the tables. By the use of this simple 
system this client reduced the fuel cost of 
steam from 15 cents down to 9 cents per 
1,000 pounds from and at 212 degrees, and 
without the application of scientific informa- 
tion after the method was once put into prac- 
tice. 

Another simple but very useful instrument 
in connection with boiler efficiency work is 
the cost of evaporation curve. The curve 
illustrated in Fig. 18 was plotted by Mr. S. 
Milton Clark, M. E., for the Isolated Plant. 
This embodies in graphic form the essentials 
of Table II already given. 



4 




^• uu 2.U0 pael Cost '-^ per Ton of 2,000™" Pounds *.**-****«. 

Fig. 18. Diagram Showing Cost of Evaporating 1,000 Lb. of Water at Different Rates of Evaporation, and 
Prices of Fuel 



BOILER EFFICIENCY SYSTEMS 245 

It is necessary to know only the cost of the 
coal per 2,000 pounds and the evaporation 
per pound in order to use the curve, which 
directly indicates the fuel cost of evaporating 
1,000 pounds of water. 

If the evaporation is taken as "actual" the 
result will be actual, or the equivalent evap- 
oration may be used (equivalent evapora- 
tion — actual evaporation X factor of evap- 
oration), in which case the curve will show 
the fuel cost of evaporating 1,000 pounds of 
water into steam from and at 212 degrees F. 

It may be of interest to note that the effi- 
ciency system described on pages 239 to 241 
inclusive is in successful operation. The set 
standard of efficiency is being maintained and 
the firemen are receiving their bonuses. 
Needless to say the results are equally grati- 
fying to both the firm and firemen. 



Chapter XI 
BOILER TESTS 

A LL the following tests were made in fac- 
-**■ tory boiler plants, and the results and 
conditions are typical of the various kinds of 
boiler and furnace equipment indicated. 

Tests on Bituminous Coal in Internally 
Fired Manning Type Upright Boilers 

The following are records of three tests 
made on boilers in the same plant. The wide 
difference in the efficiencies of tests Nos. 1 
and 3 is chargeable to operation alone. The 
term " operation " includes the cleanliness of 
the boiler heating-surfaces inside and out, the 
rate of driving, the skill of firing, all of which 
are under human control. These tests show 
the absolute necessity of keeping the factory 
boiler plant under a careful efficiency system 
so that it will at once become known when the 
performance falls off. Test No. 3 was made 
about three years after tests Nos. 1 and 2, 
246 



BOILER TESTS 247 

and it was not known how long the heavy loss 
shown by test No. 3 had been going on. 

It is also to be noted that when this type of 
boiler is forced there is a decided tendency to 
increase the percentage of CO in the flue 
gases, and there is an equally strong tendency 
to increase the escape of unburned volatile 
hydrocarbons, especially immediately after 
tiring. 

The reason is that the gases pass very 
quickly from the furnace into the small fire- 
tubes of the boiler, with such speed that there 
is not sufficient time for their complete dif- 
fusion with the oxygen. Furthermore, the 
water-legged firebox reduces the temperature 
of the combustion space, which factor further 
retards complete combustion. When the fuel 
gases have once entered the tubes their tem- 
perature is so quickly reduced that further 
combustion is practically impossible. 

A similar chilling effect takes place also on 
the standard type of water-tube boiler (un- 
less a special furnace is provided) which 
makes this kind of boiler more of a smoke 
producer than one of horizontal tubular de- 
sign. The water-tube boiler has the advan- 
tage over the vertical upright fire-tube boiler 
in the possession of a fire-brick furnace which 
helps to elevate and maintain the tempera- 
ture of combustion. 



248 



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BOILER TESTS 255 

The vertical upright has the counter ad- 
vantage of lower radiation losses, and the 
best way (for a simple rule) to fire the Man- 
ning type is to produce a flame no longer than 
the height of the firebox, so that combustion 
is completed before the gases enter the tubes. 
This is possible by regulation of the air sup- 
ply and by guarding against undue forcing. 
The flame length is approximately directly 
proportional to the degree of forcing (or rate 
of combustion) and inversely proportional to 
the air supplied per pound of fuel. 

Forcing a fire makes more gas, which in- 
creases its velocity, thus drawing out the 
flame. Eeducing the air supply makes a 
longer flame because the reduced supply of 
oxygen must be given a longer time to ' ' find ' ' 
and burn the combustible gases. Thus by the 
time the oxygen molecules have found their 
mates in the combustible gases, they have 
traveled a greater distance in the combustion 
chamber and the flame is longer. Where the 
flame stops, combustion stops also, whether 
it be complete or incomplete. 

Tests on Bituminous Coal with Down-draft 
Grates and Horizontal Tubular Boilers 

The following tests were made under reg- 
ular daily operating conditions in a New 



256 PREVENTING POWER-PLANT LOSSES 

England factory, and the high efficiencies ob- 
tained were checked up over a long period of 
time by means of daily coal and water-weigh- 
ing records which proved the performances 
herewith quoted to be average and not special 
test results. Figs. 19 and 20 show the type 
of furnace equipment and a detail of the 
water grate. 

Fig. 20. Hawley Water-tube Grate 

Showing plugs opposite tubes for cleansing purposes when 
necessary 

The operation of the system consists in fir- 
ing the green coal upon the upper grate, from 
which the combustion of the greatest part 
occurs. The burning takes place at the under 
surface of this bed of fuel which reaches a 
temperature of incandescence while the up- 
per surface remains comparatively cool. The 
result is that the volatile portion of the fresh 
coal must pass downward (by the action of 
the draft) through the incandescent layer 



BOILER TESTS 257 

which by intimate contact raises these fuel 
gases and air to a high combustion tempera- 
ture. This process prevents the production 
of smoke and practically insures complete 
combustion. The CO gas from the top grate 
must also become heated in a similar manner. 

As the coal becomes coked and crumbles, 
the smaller particles of coke fall through the 
wide spacing of the water grate upon the 
secondary grate with fine air spacing at the 
bottom, which has its own draft door under- 
neath. This fire may therefore be separately 
regulated to make possible a correct adjust- 
ment of the air supply. The two fires mingle 
between the upper and lower grates, the 
water grate receiving its air supply through 
the firing door over the top of the green coal. 
Therefore since this door is open all the time, 
the great inrush of cold air which occurs 
when an ordinary furnace is fired is entirely 
eliminated. 

This furnace of course adds a certain com- 
plication to the boiler itself due to the water 
grate and the tubes connecting it to the 
boiler, and the equipment must be scrupu- 
lously guarded to prevent the possibility of 
burning or sagging of the grates and tubes. 
These tests are of particular interest as an 
indication of the economy of combustion ob- 
tainable with this type of furnace. 



258 



PREVENTING POWER-PLANT LOSSES 



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264 PREVENTING POWER-PLANT LOSSES 

Since the horizontal tubular boiler, hand- 
fired with soft coal without any special equip- 
ment, constitutes the most used type of steam- 
generating apparatus in factory practice, the 
following test on such an arrangement will 
be of interest. 

This setting was of a type commonly found, 
the principal exception being a return of the 
gases over the top of the boiler, a feature 
which is going out of practice on account of 
the possibility of dangerous overheating of 
this portion of the shell which, having only 
steam gas in contact with its inside surface, 
does not readily transmit the heat it receives. 

The efficiency of 66.6 per cent, which may 
be considered fairly good for this equipment 
with unskilled handling, was due largely to 
the frequency of the firing tending to main- 
tain a maximum furnace temperature with a 
consequent lowering of the losses due to un- 
burned volatile and CO gases. The spread- 
ing system of firing, the most generally used 
method, was employed, but the intervals be- 
tween firings were unusually short, being less 
than six minutes. 

Barring the cooling effect of air entering 
the fire doors, it is correct to state that the 
more often and more lightly a furnace is fired 
the higher will be its temperature and com- 
bustion efficiency. 



BOILER TESTS 



265 



TEST ON BITUMINOUS SLACK COAL WITH AN ORDINARY 

HAND-FIRED HORIZONTAL TUBULAR BOILER WITH 

STATIONARY GRATES, SHOWING "GOOD" 

RESULTS FOR THE EXISTING CONDITIONS 



Kind of fuel 

Kind of furnace 

Kind of boiler 

Method of starting and stop- 
ping test 

Date of trial 

Duration of trial 

Dimensions and Proportions 

Draft area in grate 

Width of air spaces 

Height of furnace 

Water-heating surface 

Average Temperatures, Pres- 
sures, etc. 

Of external air 

Of fireroom 

Of feed water entering boiler in 

test 

Of escaping gases from boiler. 
Steam pressure by gauge — lbs. 

per sq. in 

Force of draft between damper 

and boiler 

Force of draft in furnace 

Fuel 

Size and condition 

Weight of coal as fired ...... 



Youghiogheny slack 

Stationary grate 
Horizontal tubular 

Alternate 

May 2, 1907 
9 hours 



40 per cent 

30 in. 
1,543 sq. ft. 



53 degrees 
64 degrees 

117 degrees 
567 degrees 

112 lb. 

0.60 in. w. g. 
0.54 in. w. g. 



Slack coal 
5,800 lb. 



266 PREVENTING POWER-PLANT LOSSES 

test on bituminous slack coal — Continued 



Fuel — Continued 




Percentage of moisture in coal . 
Total weight of dry coal con- 
sumed 


3.01 
5,625 lb. 
679 lb. 


Total ash and refuse removed 
from above and below grates 


Fuel per Hour . 




Dry coal consumed per hour. . 


625 lb. 


Calorific Value of Fuel 
Calorific value by oxygen calo- 
rimeter, per lb. of dry coal. . 
Available heat in a lb. of coal 
as fired after deducting loss 
due to moisture in coal 


13,142 B.t.u. 
12,710 B.t.u. 


Water 




Total weight of water fed to 
boilers 


44,341 lb. 


Factor of evaporation 

Equivalent water evaporated 
into steam from and at 212 
degrees 


1.409 
50,889 lb. 


Water per Hour 




Equivalent evaporation per 
hour from and at 212 degrees 

Equivalent evaporation per 
hour from and at 212 degrees 
per sq. ft. of water-heating 
surface 


5,656 lb. 
3.68 1b. 


Horse Power 




Boiler horse power developed. 


163.9 



BOILER TESTS 267 

test on bituminous slack coal — Continued 



Horse Power — Continued 

Builders' rated horse power at 
12 sq. ft. per horse power. 

Percentage of rated horse 
power developed 



Economic Results 

Water apparently evaporated 
under actual conditions per 
lb. of coal as fired . 

Equivalent evaporation from 
and at 212 degrees per lb. of 
coal as fired 

Equivalent evaporation from 
and at 212 degrees, per lb. of 
dry coal 

Efficiency 

Efficiency of boiler, including 
the grates; heat absorbed by 
the boiler, per lb. of coal as 
fired, divided by the avail- 
able heat of 1 lb. of coal as 
fired after deducting loss due 
to moisture 



Method of Firing 

Kind of fire (spreading, alter- 
nate, or coking) 

Average intervals between fir- 
ings 



128.5 
128.5 per cent 



7.645 lb. 
8.774 lb. 
9.046 lb. 



66.6 per cent 

spreading 
5.57 minutes 



268 PREVENTING POWER-PLANT LOSSES 

Another test on a hand-fired horizontal 
tubnlar boiler equipped with shaking grates 
but having no return flue over the top of the 
shell is of value, in general confirmation of 
what may be regularly obtained without spe- 
cial equipment but with fairly good firing 
which in the following case was by the alter- 
nate method. 

It is interesting to note in the flue-gas an- 
alysis made during this test the feast-and- 
famine tendency of the air supply which is 
characteristic of hand firing. Thus immedi- 
ately after firing, the air in proportion to the 
coal decreases, as indicated by the rise of 
C0 2 , and just before firing the C0 2 is low, 
showing a greater excess of air. 

Various patented appliances have been de- 
vised for the purpose of equalizing the air 
supply to the requirements at all stages of 
the fire. Such inventions are generally 
speaking a failure. They tend to flood the 
furnace with air far in excess of the true 
requirements, and are likely to lower the 
temperature of the furnace during the vola- 
tilization of hydrocarbons immediately after 
firing, just when a maximum temperature is 
wanted to ignite these gases. 



BOILER TESTS 



269 



TEST ON HORIZONTAL TUBULAR BOILER WITH SHAKING 
GRATE AND HAND-FIRED 



Kind of fuel 

Kind of furnace 

Kind of boiler 

Method of starting and stopping 
test 

Date of trial 

Duration of trial 

Dimensions and Proportions 

Grate surface (7 ft. X 7 ft.). . . . 

Air space 

Percentage of draft area 

Water-heating surface 

Superheating surface 

Ratio of water-heating surface to 
grate surface 

Average Temperatures, 
Pressures, etc. 

Steam pressure by gauge 

Temperature of feed water enter- 
ing boiler 

Temperature of gases leaving 
boiler 

Temperature of air entering ash- 
pit 

Temperature of external air 

Force of draft between damper 
and boiler 

Force of draft over fire 



Bit.-run-of-mine 

Shaking grate, 

hand-fired 

Hor. tubular 

Alternate 

Feb. 7, 1911 
8hrs. 



49 sq. ft. 

5/16 in. 
35.7 per cent 
2,526 sq. ft. 

sq. ft. 

51.6 to 1 



86.5 lb. 

175 degrees 

580 degrees 

68.5 degrees 
28.2 degrees 

0.47 in. w. g. 
0.27 in. w. g. 



270 PREVENTING POWER-PLANT LOSSES 

TEST ON HORIZONTAL TUBULAR BOILER — Continued 



Average Temperatures, Pressures, 
etc. — Continued 




Force of draft at rear of com- 
bustion chamber when tested 
(4 readings) 


0.30 in. w. g. 
Snow — damp air 


Weather 


Fuel 


Weight of coal as fired 


9,095 lb. 


Percentage of moisture in coal 
Total weight of dry coal consumed 


5.07 per cent 
8,634 lb. 


Fuel per Hour 




Dry coal consumed per hour .... 
Dry coal per sq. ft. of grate sur- 
face per hour 


1,079 lb. 
22 1b. 


Calorific Value of Fuel 




Calorific value per lb. of dry coal. 

Moisture in coal as delivered to 

fireman 


12,900 B.t.u. 
5.07 per cent 


Water 


Total weight of water fed to 
boiler 


72,080 lb. 


Factor of evaporation 


1.0754 


Equivalent water evaporated into 
steam from and at 212 degrees. . 


77,514 lb. 


Water per Hour 




Water evaporated per hour from 
and at 212 degrees 


9,689 lb. 
3.84 lb 


Water evaporated per hour from 
and at 212 degrees per sq. ft. 
of water-heating surface 



BOILER TESTS 271 

TEST ON HORIZONTAL TUBULAR BOILER — Continued 



Horse Power 

Total horse power developed . . 
Builders' rated horse power at 12 

sq. ft. per horse power 

Percentage of builders' rated 

horse power developed 



Economic Results 

Water apparently evaporated un- 
der actual conditions per lb. of 
coal as fired 

Equivalent evaporation from and 
and at 212 degrees per lb. of 
coal as fired 

Equivalent evaporation from and 
at 212 degrees per lb. of dry 
coal 

Efficiency 

Efficiency of boiler including grate 
based on dry coal 

Efficiency of boiler including grate, 
based on available heat sub- 
tracting moisture loss 

Cost of Evaporation 

Cost of coal per ton of 2,000 lb. 
delivered in boiler room 

Cost of coal for evaporating 1,000 
lb. of water into steam from 
and at 212 degrees 



281 

210 

133.7 per cent 



7.92 lb. 
8.52 lb. 
8.98 lb. 

67.25 per cent 
67.5 per cent 

$2.40 
$0,141 



272 



PREVENTING POWER-PLANT LOSSES 



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BOILER TESTS 273 

Too much grate surface with a consequent- 
ly low rate of combustion and an excessive 
air supply represents a commonly found 
condition which results in a heavy loss of 
fuel. 

Such a case is illustrated in the test fol- 
lowing. The two horizontal tubular boilers 
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mal capacity. This brought into service 
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for a normal consumption of fuel per square 
foot. The draft intensity was normally 
strong and the supply of coal was abnor- 
mally low, so that the air supply far exceeded 
the requirements of the coal as fired. The 
result was an average C0 2 of only a little 
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per cent of boilers and furnaces combined. 

A peculiar circumstance connected with 
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was unable to keep up the standard steam 
pressure even with twice the boiler heating 
and grate surface that was really necessary, 
and he thought the trouble Was due to weak 
draft. The real causes of inefficiency were 
those already noted, combined with infre- 
quent firing, and when they were eliminated 
by carrying all the load on a single boiler 
with reduced grate surface and teaching him 
how to fire, the efficiency of the boiler and 



274 



PREVENTING POWER-PLANT LOSSES 



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280 PREVENTING POWER-PLANT LOSSES 

furnace jumped up to about 70 per cent. The 
immediate result was a saving of over 24 per 
cent of fuel and no difficulty in maintaining 
the desired steam pressure. In fact, the 
dampers were now kept not quite half-open. 
There was nothing unusual about the set- 
tings of these boilers, except that No. 2 had 
shaking grates. 

Boiler Tests with Anthracite 

In those districts where anthracite coal is 
available it is of essential value to know what 
performance may be expected with this fuel, 
especially in the smaller and cheaper sizes. 
For such information the following boiler 
tests made in factory plants are given. 
These will indicate the conditions surround- 
ing both good and bad practice with Nos. 2 
and 3 buckwheats together with a test on the 
higher priced No. 1 buckwheat made under 
very ordinary conditions. 

The standards governing the sizes of 
anthracite coals vary, but the schedule of 
sizes as recommended by the American So- 
ciety of Mechanical Engineers, and as here 
illustrated in Fig. 21, may properly be ac- 
cepted and used. 

Two tests, given in detail on pages 282 to 
290, were made in the same plant on No. 2 
buckwheat mixed with a portion of soft coal. 





N24- BUCKWHEAT or CULM 



Standards for anthracite-coal sizes as recommended by the 
American Society of Mechanical Engineers and printed in the 
Society's Journal, November, 1912. 

Screen or Opening 

(Circular) Through or Over 

Which Coal Will 



Name 



No. 1 buckwheat 

No. 2 buckwheat 

No. 3 buckwheat 

No. 4 buckwheat or culm . . 



Pass, Inches 
Through Over 

I I 



The sizes specified by the New York City Department of 
Water Supply, Gas and Electricity are practically the same as 
the above except for pea coal, which is specified as coal which 
will pass through f-inch and over |-inch openings. 



N22- BUCKWHEAT OR RICE 

Fig. 21. Actual Sizes of Anthracite Coal 



BOILER TESTS 281 

Conditions of both tests, natural draft, com- 
mon design of furnaces with B. & W. boilers. 
Both tests show poor results as to boiler ca- 
pacity. Test A gave a good efficiency and 
test B a very low efficiency. 

The conditions governing this wide varia- 
tion in economic performance are readily ob- 
tainable from an analysis of the following 
records which ar"e briefly discussed at their 
end. 

The rating in test A was higher than in 
test B, which may be accounted for by the 
greater intensity of draft in the furnace, and 
by the shorter firing interval as recorded. 
Both ratings were low, as may be expected 
• with a natural draft of normal intensity with 
this coal. 

The great difference in efficiency (test A == 
69.37 per cent and test B == 47.77 per cent) in 
favor of test A is principally due to the fol- 
lowing conditions : 

A firing interval of 16 minutes in test A 
(instead of 23% minutes) operated to pro- 
duce a more nearly uniform furnace temper- 
ature. 

The draft area through the grate in test A 
was only 6.13 per cent, whereas the boilers of 
test B had grates with 40 per cent draft area, 
which largely accounts -for the tremendous 
excess of air as denoted by the average of 



282 



PREVENTING POWER-PLANT LOSSES 





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290 PREVENTING POWER-PLANT LOSSES 



FLUE-GAS ANALYSIS TAKEN DURING TEST ON BOILERS 
NOS. 1 AND 2 

CO 

Sample Notes per ^ 

1. Sample 8:56 a.m.— Boiler No. 1 6.6 

2. Sample 9 :20 a.m. — Boiler No. 2, ash doors 

all open 6.6 

3. Sample 9:53 a.m. — Boiler No. 1, 12 minutes 

before cleaning 8.6 

4. Sample 10:42 a.m.— Boiler No. 2, 12 min- 

utes after firing 4.0 

5. Sample 11 :13 a.m. — Boiler No. 2, ash doors 

Yi open 6.0 

6. Fired 11:50 a.m. — Boiler No. 1, sample 3 

minutes after firing 11.0 

7. Sample 12:43 a.m. — Boiler No. 1, ashpit 

closed tight 5.0 

8. Fired 1 :22 p.m.— Boiler No. 2, sample 1 :25 

p.m., 3 minutes after firing 7.0 

9. Fired 1:45 p.m. — Boiler No. 2, sample 3 

minutes after firing 9.5 

10. Fired 2:00 p.m. — Boiler No. 1, ash doors 

Yz open, 7 minutes after firing 7.2 

11. Fired 2:25 p.m. — Boiler No. 1, 5 minutes 

after firing 7.8 

12. Fired 2 :48 p.m.— Boiler No. 2, ash doors Y 

open, 17 minutes after firing 8.1 

13. Sample 3 :29 p.m. — Boiler No. 2, ash doors 

Yi open, just before raking 5.8 

14. Fired 3:44 p.m.— Boiler No. 1, sample 3:52 

p.m., ash doors Y2 open 7.0 

15. Raked 4:15 p.m. — Boiler No. 1, sample 6 

minutes after raking 9/0 

16. Sample 4:49 p.m. — Boiler No. 2, 7 minutes 

after firing 7.0 

Average per cent C0 2 7.5 



BOILER TESTS 291 

7.5 per cent C0 2 as compared to 10.4 C0 2 for 
test A. 

The buckwheat coals may be burned with 
good results under natural draft as indicated 
by test A, but the horse-power output of the 
boiler will be below normal rating with chim- 
neys of average height. When the chimney 
is of a height to give an intensity of draught 
sufficient for high ratings, the usual result is 
a very large excess of air in the furnace with 
a consequently low efficiency. 

For burning the buckivheats the volume of 
air required is less per pound than for soft 
coals, but the intensity or pressure of draft 
must be greater in order to penetrate the 
more resistive bed of fuel. When a high 
stack is used to obtain the penetration, the 
stack damper must be opened wide to secure 
the maximum intensity at the furnace. This 
also increases the volume, which is not de- 
sired. Of course this ill effect can be coun- 
teracted by regulating the volume of air by 
means of the ashpit doors and leaving the 
stack and uptake dampers wide open to se- 
cure the desired intensity. But this requires 
very skillful operation as well as a high 
chimney, and furthermore the draft condi- 
tions change with the weather. 

Consequently the most surely satisfactory 
method of burning the fine sizes of anthracite 



292 PREVENTING POWER-PLANT LOSSES 

is by the employment of mechanical or steam 
draft arranged to produce a pressure of air 
under the grate. A chimney of moderate 
height is needed to carry off the gases, but 
need be of no such height as would be re- 
quired with natural draft alone. "With this 
combination it is readily practicable to obtain 
separate regulation of the intensity of draft 
(for penetration) and the volume of draft for 
correct air supply. Changing the speed of 
the fan varies the intensity to any desired 
pressure, and the damper in the uptake is 
independently throttled down to reduce the 
volume of air to a minimum for good com- 
bustion. 

It is of interest to note at this point that in 
New York city, where the small sizes of. 
anthracite constitute the most used fuel, very 
great losses exist owing to surplus air in the 
fires, while losses due to incomplete combus- 
tion of the coal are utterly insignificant in 
comparison. The cure is less air, and the 
surest way to supply the less amount of air 
is to install forced draft. This sounds like a 
paradoxical statement, but in this case forced 
draft means the ability readily to control 
both the volume of air and the intensity of 
draft and to control them separately and in- 
dependently. The higher the chimney which 
furnishes the draft for burning buckwheat 



BOILER TESTS 293 

coals, the larger will be the probable saving 
in fuel that can be made by installing forced 
(and controlled) draft. I use the term 
"forced draft" as applying to any means of 
creating a pressure of air under the grate of 
the furnace, and in contra-distinction to "in- 
duced draft", in which case a fan is employed 
to exhaust the air from the boiler uptake. 
Induced draft is open to the same objections 
as natural chimney draft for burning the 
buckwheats since it operates and is controlled 
in the same manner. 

Forced draft may be produced either by 
means of fans of various types, or by the use 
of steam jets which induce a current of air 
through a tube communicating inwardly to 
the ashpit of the furnace. This latter consti- 
tutes the simplest form of forced draft. In 
the past its principal drawback was its very 
large consumption of steam as compared to 
the amount required to operate a fan. But 
in recent years scientific design of steam jets 
has largely overcome this objection with the 
best types of steam blowers, and in small in- 
stallations they will, with their added advan- 
tage of simplicity, often compete with fan- 
draft designs. In such cases the greatest 
drawback to the steam- jet system is the 
noise, or the roar of the escaping steam 
which may be disconcerting to the firemen 



294 PREVENTING POWER-PLANT LOSSES 

and hard on one's nerves. This may be 
partly mitigated by methods of muffling. 

The following acceptance test was made 
on a steam- jet system burning straight No. 3 
buckwheat and a very thorough test was 
made to determine the steam used by the 
blowers. This was found to be only 2.35 per 
cent of the boiler output when operating at 
111.5 per cent of rated capacity (boiler rated 
at 12 sq. ft. per horse power). When pur- 
chasing a system of this kind specifications 
should be drawn to cover net efficiency based 
on the useful steam generated after deduc- 
tion of the steam consumed by the blower. 

For all usual installations of buckwheat- 
burning systems a possible under-grate pres- 
sure of 1% inches of water should be pro- 
vided, though for special cases where fires 
cannot be cleaned for long periods the resist- 
ance to air passage builds up as the fire bed 
increases in thickness and a much greater 
pressure is required. 

In ordinary factory installations about 
%-inch water pressure is sufficient with a 
clean fire, and this is gradually increased as 
the ash accumulates until just before clean- ' 
ing it is usual to require between 1-inch and 
1%-inch water pressure in the ashpit. 

Except in extraordinary cases the fan (or 
steam jets) overcomes only that part of the 



BOILER TESTS 295 

total draft resistance which is caused by the 
grate and the fire bed, so that atmospheric 
pressure or, more usually, a slight vacuum 
exists over the burning fuel. As a fireman 
would express it, "the fan shoves the draft 
through the grate and the fuel. Then the 
chimney picks it up and does the rest of the 
work. There is a push under the fire and a 
pull over it." 

There should be no pressure in the fur- 
nace or the flames will blow out of the fire 
doors when opened. "Also there should not 
be a strong vacuum, or cold air will rush in 
to cool the furnace while firing. 

TEST ON NO. 3 BUCKWHEAT COAL WITH STEAM-IN- 
DUCED FORCED DRAFT, ON A HORIZONTAL TU- 
BULAR BOILER. COMBUSTION ARCH BACK 
OF THE BRIDGE WALL 

This test is typical of good results on No. 3 buck- 
wheat coal in a well-designed furnace. Steam used 
for operation of draft — 2.35 per cent of boiler output. 



Kind of furnace, boiler set 4 
feet above grate, combus- 
tion arch in front of blow-off 

Kind of boiler, 6 ft. x 18 ft.- 
124 3 -in. tubes 

Kind of fuel 

Method of starting and stop- 
ping test 



XY System 

Horizontal tubular 
/ No. 3 buckwheat 
\ anthracite 

Alternate 



296 



PREVENTING POWER-PLANT LOSSES 



TEST ON NO. 3 BUCKWHEAT 


1 coal — Continued 


Grate surface, sq. ft 


42 sq.ft. (6 ft. X 7 ft.) 
1,877 sq. ft. 

44 .7 to 1 


Water-heating surface, sq. ft . . 

Ratio of water-heating surface 

to grate surface 


Width of draft openings in 
grate 


5/16-in. round holes 


Per cent draft area in grate . . . 

Total Quantities 
Date of trial 


8.5 
Dec. 13, 1912 


Duration of trial, hours 

Weight of coal as fired, lbs 

Percentage of moisture in coal. 
Total weight of dry coal con- 
sumed 


8 
5,907 
9.58 

5,341 lb. 


Total ash and refuse cleaned 
from top of grate 


726 lb. 


Percentage of same compared 
to dry coal burned 


13.6 


Water actually evaporated 

Water used by blowers 

Useful net actual evaporation . 

Factor of evaporation 

Equivalent useful water evap- 
orated from and at 212 de- 
grees 


41,358 lb. 

974 lb. 

40,384 lb. 

1.19 

48,057 lb. 


Hourly Quantities 

Coal as fired consumed per 
hour 


738 lb. 


Dry coal consumed per hour . . 

Dry coal per sq. ft. of grate 

surface per hour 


668 1b. 
15.9 1b. 


Total water actually evapo- 
rated per hour 


5,1701b. 





BOILER TESTS 



297 



test on no. 3 buckwheat coal — Continued 



Hourly Quantities — Continued 

Total equivalent evap. per hr. 
per sq. ft. of heating surface 

Equivalent evap. per hr. used 
by the two No. 7E blowers . 

Total equivalent evaporation 
per hr. from and at 212 de- 
grees 



Average Pressures, Tempera- 
tures, etc. 

Steam pressure by gauge 

Temperature of feed water en- 
tering boiler 

Temperature escaping gases 
from boiler 

Temperature air entering ash- 
pit 

Force of draft between damper 
and boiler, water gauge, 
inches 

Draft pressure under grate, 
inches water 

Draft pressure over grate 



Horse Power 

Total horse power developed 

Horse power developed — correct- 
ed for steam used by the blow- 
ers 

Builders' rated horse power 
at 12 sq. ft. per horse power 

Percentage rated useful horse 
power developed, useful steam 

Percentage of horse power used 
by the blowers 



3.26 lb. 
145 lb. 

6,152 lb. 

112 lb. 
67 degrees 
493 degrees 
40 degrees 

0.273 vacuum 

0.415 pressure 
0.15 vacuum 

178.3 

174-1 
156.0 
111.5 per cent 
2.35 per cent 



298 



PREVENTING POWER-PLANT LOSSES 



test on no' 3 buckwheat coal — Continued 



Horse Power — Continued 

Boiler horse power used by the 

blowers 

Economic Results 

Water apparently evaporated 
under actual conditions per 
lb. of coal as fired 

Water actually evaporated cor- 
rected for steam used by 
blowers, per lb. of coal as fired 

Equivalent useful evaporation 
per lb. of coal as fired 

Equivalent evaporation per lb. of 
dry coal corrected for steam 
consumption of blower 

Efficiency 
Calorific value of the dry coal 

per lb 

Moisture in coal as delivered to 

firemen 

Net efficiency of boiler including 

grate based on dry coal .... 

Cost of Evaporation 

Cost of coal delivered at plant 

Cost of coal for evaporating 1 ,000 

lb. of water from and at 212 

degrees 

Cost of coal for evaporating 
1,000 lb. of water from and 
at 212 degrees, adding 10 
cents per ton to include un- 
loading and handling to fire- 
room 



4.2 

7 .01 lb. 

6.84 1b. 
8.13 1b. 

9.00lb. 

12,670 B.t.u. 

9.58 per cent 

69 per cent 

.80 for 2,240 lb. 

$0.0988 



$0.1043 



BOILER TESTS 299 

NOTES ADDED TO BOILER TEST 

Tests Made on Percentage of C0 2 (Carbon 

Dioxid <* ■ percent 

Sample taken at 2 p.m., about 3 minutes after 

firing, blast on 15 

Sample taken at 2:20, about 5 minutes after 

firing, blast on 14 

Sample taken at 2 :45, fire well burned, blast on 11.8 
Sample taken at 3 :02, about 2 minutes after fir- 
ing, blast on 11 

Sample taken at 3:20, just after leveling fire, 
blast on 10 

The above analyses show a good grade of 
combustion. The C0 2 should approach 15 
per cent as nearly as possible for the best 
factory work and should not go below 10 per 
cent with No. 3 buckwheat or other hard 
coals. "When the C0 2 drops below 10 per 
cent too much air is being admitted to the 
fire, and the damper should be throttled 
down to prevent this excess and the holes in 
fire bed carefully covered, and also a little 
greater depth of fire will tend to work to- 
wards reducing this excess air. 

NOTES ON FIRING 

The fire was cleaned at 8 a. m. The 
cleaning was completed and fire freshly cov- 
ered with coal by 8:30, when the test was 
started. The fire was cleaned at noon, the 
noon hour being thirty minutes at this plant. 
The boiler was allowed to blow of! twenty to 



300 PREVENTING POWER-PLANT LOSSES 

twenty-five minutes during this noon clean- 
ing operation. 

The fire was finally cleaned at 4 p. m. and 
the cleaning was completed and fire freshly 
covered with coal by 4 :30 p. m. when the test 
was stopped. 

There was, therefore, the same amount of 
unburned coal on the grate at the end as 
at the beginning of the test so that the 
amount fired between 8 :30 and 4 :30 was the 
amount which was actually burned during the 
test and charged against the boiler and the 
steam produced. 

FIRING 

The spreading method of firing was used 
throughout the test, and there was usually 
only a small interval of time between the cov- 
ering of one side of the furnace and the cov- 
ering of the other side. From 8 :30 to 12 :50, 
or about four hours and a half, there were 
19 coverings of coal including the cleaning. 
Between 12 :50 and 4 :30, or about three hours 
and a half, there were about the same num- 
ber of coverings. The firing during the first 
period mentioned was done by the expert 
fireman of the XY Mfg. Co., and in the after- 
noon period the fire was handled by the regu- 
lar factory fireman with the exception of 
the final cleaning which was done by the XY 



BOILER TESTS 301 

man. It is my judgment that the regular 
fireman kept as good a fire as the XY man; 
and there is no reason why the efficiency 
shown in this test should not be kept up con- 
tinuously. 

The following test on No. 1 buckwheat was 
made in the same plant as the test on No. 3 
buckwheat immediately preceding. The plant 
originally burned the more expensive coal 
with natural draft and was then ' ' put over ' ' 
on the No. 3 buckwheat with forced draft. 
A comparison of the costs of evaporation of 
the respective systems will indicate the per- 
centage of saving effected by this change. 
The advisability of such a change depends 
upon efficiencies and coal prices, dependabil- 
ity of coal supply, and upon the human fac- 
tor. This latter may never be disregarded 
with impunity in changing over from one 
kind of coal to another which involves new 
firing methods. 

TEST ON NO. 1 BUCKWHEAT; ANTHRACITE COAL, HAND 
FIRED 

Horizontal tubular boiler, natural draft, combus- 
tion baffle arch under boiler. 



Kind of fuel .... 
Kind of furnace . 



No. 1 Buckwheat 

Anthracite . 
[ Stationary grate, 
( special combustion 

arch under boiler 



302 



PREVENTING POWER-PLANT LOSSES 



test on no. 1 buckwheat — Continued 



Kind of boiler 


Horizontal tubular 


State of the weather 


Clear and cold 


Method of starting and stop- 
ping test 


Alternate 


Date of trial 


12/18/13 
6 hrs., 4 min. 


Duration of trial 


Dimensions and Proportions 
Grate surface 


6ft.x6ft.=36sq.ft. 
36 in 


Height of furnace 


Approximate width of air spaces 
in grate 


1/4 in. to 5/16 in. 

About 33 per cent 
f 6 ft.xl7 ft. with 82 
\ 4 in. tubes 
1,598 sq. ft. 


Proportion of air space to whole 
grate surface 


Dimensions of boiler 


Water heating surface 

Superheating surface 


Ration of water-heating surface 
to grate surface 


44 4 to 1 


Steam pressure by gauge, aver- 
age 


39 1b. 


Force of draft between damper 
and boiler 


0.42 in water 


Force of draft in furnace 

Force of draft or blast in ashpit 

Average Temperatures 
Of external air 


0.32 in. water 
Atmospheric 

31 degrees 

68 degrees 

59 degrees 

542 degrees 

Clean but wet 


Of fireroom 


Of feed water entering boiler . . 
Of escaping gases from boiler . . 

Fuel 
Size and condition 


Weight of coal as fired 

Percentage of moisture in coal . 


3,905 lb. 
6.98 per cent 



BOILER TESTS 



303 



test on no. 1 buckwheat — Continued 



Fuel — Continued 
Total weight of dry coal con- 
sumed 


3,632 lb. 


Total ash and refuse 


650 lb. (approx.) 

599 lb. 
16.6 lb. 


Fuel per Hour 
Dry coal consumed per hour. . 
Dry coal per sq. ft. of grate sur- 
face per hour 


Calorific Value of Fuel 
Calorific value by oxygen cal- 
orimeter, per lb. of dry coal 

Water 
Total weight of water fed to 
boiler 


12,285 B.t.u. 
23,920 lb. 


Factor of evaporation 


1 . 1833 


Equivalent water evaporated 
into steam from and at 212 
degrees , 


28,3051b. 


Water per Hour 
Actual water evaporated per 
hour 


3,936 lb. 


Equivalent evaporation per 
hour from and at 212 degrees 

Equivalent evaporation per 
hour from and at 212 degrees 
per sq. ft. of water-heating 
surface 


4,660 lb. 
2.91 lb. 


Horse Power 
Boiler horse power developed . . . 
Builders' rated horse power at 

10 sq. ft. per horse power . . . 
Percentage of builders' rated 

horse power developed 


135 
160 

84.4 v er cen t 



304 



PREVENTING POWER-PLANT LOSSES 



test on no. 1 buckwheat — Continued 



Economic Results 
Water apparently evaporated 
under actual conditions per 
lb. of coal as fired 


6.12 lb. 


Equivalent evaporation from 
and at 212 degrees per lb. of 
coal as fired 


7.25 lb. 


Equivalent evaporation from and 
at 212 degrees per lb. of dry coal 

Efficiency 
Efficiency of boiler, including 
the grate; heat absorbed by the 
boiler per lb. of dry coal, di- 
vided by the heat value of 1 lb. 
of dry coal (A. S. M. E. Code) 

Cost of Evaporation 
Cost of coal per ton of 2,240 lb. 
delivered in boiler room .... 
Cost of fuel for evaporating 
. 1,000 lb. of water under ob- 
served conditions 


7.793 lb. 

61.5 per cent 

$2.75 
$0,207 


Cost of fuel used for evaporating 
1,000 lb. of water from and at 
212 degrees 


$0.1693 


Method of Firing 
Kind of firing (spreading, alter- 
nate, or coking) 


Spreading 
About 5 in. 

16.6 min. 

2hrs. 

/ 10.3 per cent (av- 


Average thickness of fire 

Average intervals between fir- 
ings for each furnace 

Average interval between times 
of leveling or breaking up. . . 

Analysis of the Dry Gases 

Carbon dioxide (CO2) 




\ erage) 



BOILER TESTS 305 

Methods for Boiler Testing 

• The following description of the author's 
method of weighing the feed water in a boiler 
test is herewith presented in connection with 
Fig. 22. An extremely accurate water 
weigher is used which automatically records 
the actual weight of the water fed to the boil- 
ers. By actual test this weigher shows a 
maximum error of one-third of one per cent 
and is far superior to hand-operated water 
tanks for accurate boiler testing. 

The water weigher as shown at the right in 
Fig. 22, on page 306, is set above the sump 
tank, which may take the form of a hogshead 
or any kind of a tank of suitable size. Either 
hot or cold water under pressure is piped "to 
the water weigher, its admission being regu- 
lated by a hand valve operable from the floor. 

A separate feed pump, as shown, draws 
the water from the sump tank and delivers it 
through a special connection to the boiler or 
boilers to be tested. The diagram shows this 
special connection in its proper location for 
testing all the boilers in the battery together. 
When it is desired to test a single boiler, the 
connection shown at A is inserted in the indi- 
vidual branch of the feed line to any boiler as 
designated at A-l. 




a 



o 



o 
V 



306 




307 



308 PREVENTING POWER-PLANT LOSSES 

This special connection consists simply of 
a tee, three valves, and a drip connection with 
proper nipples as shown in the detail of Fig. 
22. 

One purpose of using this special piping 
arrangement is to allow quick starting and 
stopping of a boiler test. That is to say, by 
operating the valves of the special connec- 
tion the boilers may be changed over instant- 
ly from the testing feed pump to the regular 
feed pump, and vice versa. This piping ar- 
rangement also shows up any leakage that 
might occur either from the boilers back 
through the regular feed pump while the test 
is on, or from the regular feed pump into the 
boilers during such period. The leak in either 
direction will be indicated by the drip con- 
nection as shown between the two valves on 
the horizontal run, the cock or valve being 
left open during the boiler test. One excel- 
lent feature of this standard connection is 
that it may be cut to accurate length and in- 
serted in half an hour at noon-time or at 
night without disturbing the regular opera- 
tion of the plant. 

A convenient location for the feed-water 
thermometer is indicated on the suction of 
the test pump. This thermometer is of spe- 
cial construction and is very accurately cali- 
brated. 



boiler tests 309 

Flue Gas and Deaft Connections eor Boiler 
Testing 

This diagram (Fig. 23) shows the author's 
method for obtaining samples of flue gas for 
analysis from any boiler in the battery being 
tested. 

This method makes double use of the sam- 
ple piping from the uptake of each boiler. 
First this piping connects to the draft gage, 
for measuring the intensity of draft ; and sec- 
ond, it furnishes a practically continuous 
sample of flue gas for analysis in the Orsat 
machine which stands on the table. A %-inch 
standard gas pipe is run from the uptake of 
each boiler and connects to a cross or mani- 
fold at the point 1 close by the table. Thus 
the uptake of any boiler may be connected to 
either the draft gage or the flue-gas machine 
as desired. 

The gas is drawn through the burette of 
the Orsat machine by means of a water oper- 
ated ejector 2 which is connected to the top 
of the leveling bottle 3. By breaking the con- 
nection between the water bottle and the ejec- 
tor a sample of gas is entrapped and water- 
sealed in the burette of the Orsat machine. 
The dotted line shows a piping connection 
between the zero end of the Ellison draft 
gage and the furnace of the boiler. By its 



310 PREVENTING POWER-PLANT LOSSES 

use the frictional loss of draft between the 
furnace and the boiler uptake may be ob- 
tained on the draft gage in the form of a 
direct reading without calculation. 



•Chapter XII 
COMBUSTION 

THE object of this chapter is to set forth 
in a convenient form the fundamental 
physical and chemical data relating to the 
combustion of fuel and to point out certain 
errors which are prevalent in connection 
with the use of combustion analysis for the 
determination of chimney losses. So much 
misunderstanding exists even among engi- 
neers in relation to the problems here in- 
volved that the thorough study given to this 
chapter is rendered well worth the effort it 
has required. 

The one greatest loss in steam-boiler op- 
eration is that due to the heat carried away 
by the dry chimney gases. This loss (L) is 
equal to the weight of the dry products of 
combustion multiplied by their average spe- 
cific heat and by the difference in tempera- 
ture between the air in the fireroom and the 
escaping gases from the boiler. 
311 



312 PREVENTING POWER-PLANT LOSSES 

Disregarding sulphur, carbon and hydro- 
gen are the only heat-producing elements in 
a coal, and of these carbon alone produces 
dry gases upon combustion. The hydrogen 
burns to H 2 and together with the water 
contained in the coal produces the "wet" 
portion of the products of combustion, and 
the loss due to these constituents may best be 
calculated separately. Furthermore, the hy- 
drogen constituent of a coal rarely exceeds 
23 per cent of the heat value of the coal. We 
are therefore first concerned with the com- 
bustion of the carbon and its attendant chim- 
ney loss. As will be shown later in this chap- 
ter, a chimney-loss curve constructed on the 
basis of burning pure carbon and relating 
this loss to volumetric C0 2 as determined 
by an Orsat gas apparatus does not hold good 
for burning coal. This fact seems to be al- 
most universally disregarded by the great 
majority of "combustion engineers." 

Our first duty, however, is to construct 
such a pure-carbon curve as carefully as pos- 
sible, and then to construct a curve for an 
actual coal in order in the course of the ar- 
gument to develop quantitatively the differ- 
ences that occur. 

It is most common practice to find pure- 
carbon C0 2 curves applied for the determi- 
nation of chimney losses. The results thus 



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COMBUSTION" 313 

obtained will be erroneous because we burn, 
not pure carbon, but coal which contains 
other constituents. In addition to this, even 
if we did have pure-carbon fuel many per- 
sons would obtain wrong deductions from the 
curve, for the reason that the losses of the 
curve are based not on the total carbon fed 
to the furnace but on that part only of the 
carbon which is burned and gasified. Fur- 
thermore, in developing the pure-carbon 
curve shown in Fig. 24, I have found serious 
errors in a set of curves which were looked 
upon as standard. 

We will now proceed to consider the com- 
plete combustion 1 of a pound of carbon from 
a furnace grate. In the following discussion 
the nomenclature given in the explanatory 
table on pages 314 and 315 will be employed. 
These symbols for convenience have been 
made identical with those used by Ed- 
ward A. Uehling in his valuable paper on 
"Combustion and Boiler Efficiency" pre- 
sented before the American Society of Me- 
chanical Engineers in 1910. Some of his 
method of reasoning has been employed" in 
the present discussion. 



1,1 Complete combustion" means entire oxidation of all the fuel con- 
stituents. Thus C must burn to CO2 and H to H2O. "Perfect combus- 
tion" should be defined as complete combustion with zero excess oxygen 
or air. The term "chemical combustion" may be used interchangeably 
with "perfect combustion". 
































' 
















■ 








,=i -_: J 



Fig. 24. Puee-Carbon Curve 



314 PREVENTING POWER-PLANT LOSSES 

L d = Heat in B.t.u. carried away by dry chimney 

gases per weight of fuel containing one pound 

of carbon burned. 
Wd = Pounds of dry chimney gases per weight of 

fuel containing one pound of carbon. 
L = Pounds of dry chimney gases per pound of 

combustible burned. 
W = Pounds of dry chimney gases per pound of 

combustible. 
L c = B.t.u. loss due to heat value of CO in chimney 

gases per pound of carbon. 
L c i = B.t.u. loss due to heat value of CO in chimney 

gases per pound of combustible burned from 

grate. 
A = Pounds of air consumed in burning a weight 

of fuel containing a pound of carbon. 
A c = Theoretical pounds of air required to burn a 

pound of carbon. 
A h = Theoretical pounds of air required to burn a 

pound of hydrogen. 
A e = Pounds of air in excess of that theoretically 

required to burn a weight of fuel containing a 

pound of carbon. 

H a = H — in which 

8 

H = Pounds of hydrogen in a weight of fuel con- 
taining one pound of carbon. 
O = Pounds of oxygen in a weight of fuel contain- 
ing one pound of carbon. 
That is H a = that portion of hydrogen in the 
fuel which requires a supply of oxygen (or 
air) for its combustion. This calculation 
assumes that the oxygen content of the fuel 
is used for burning its equivalent of hydro- 
gen. Then the remaining hydrogen (H a ) 
plus the carbon determines the amount of 
air that must be supplied for combustion 
through the furnace. 



COMBUSTION 315 

= Volumetric percentage of C0 2 by Orsat an- 
alysis of chimney gases. 

= Volumetric percentage of CO by Orsat an- 
alysis of chimney gases. 

= Mean specific heat of dry chimney gases be- 
tween the extremes of zero and perfect com- 
bustion. 

= Temperature Fahrenheit of gases escaping 
from boiler. 

= Temperature Fahrenheit of air in fireroom. 



Deduction of Dry-Gas Chimney Loss in the 

Complete Combustion of One Pound 

of Puke Carbon to C0 2 with 

Vaeying Amounts of Air 

L d = W d XS(T — t). 

For perfect combustion W d is equal to the 
pound of carbon plus the air chemically re- 
quired for its combustion. For the determi- 
nation of the weight of this air we have the 
chemical equation for the combustion of car- 
bon: — 

C + 2 = C0 2 

Expressed in atomic weights of the ele- 
ments we have : — 

12 4- 32 = 44 2 I Hence for each weight or 

32 
pound of carbon we must supply — = 2.666 weights 

or pounds of oxygen. 



316 PREVENTING POWER-PLANT LOSSES 

Now according to Sir William Eamsay, the 
composition of atmospheric air is 23.024 
parts of oxygen and 75.539 parts of nitrogen 
and 1.437 of argon by weight. The nitrogen 
is inert and plays no part in combustion ex- 
cept as a diluent of the resulting gases, and 
argon as far as present knowledge goes is 
equally inert and may be treated as nitrogen 
in our combustion analysis. Hence calling 
the oxygen constituent of air 23 per cent by 
weight we must supply 

2 - 666 11 A IK 

023 = 1L6 lb - 

of air to furnish sufficient oxygen for the 
perfect chemical combustion of a pound of 
carbon, and for this condition W d — 1 -f- 
11.6 = 12.6 pounds products of combustion 
per pound . of carbon. The composition of 
these products will be 

79 N 
21 C0 2 

by volume and our Orsat apparatus would 
show 21 per cent C0 2 . 

This follows from Avagadro's Law which 
states that equal volumes of all gases under 
the same temperature and pressure contain 
the same number of molecules, and, converse- 
ly, when the number of molecules is un- 



COMBUSTION" 317 

changed the volume is constant. Now when 
oxygen unites with carbon the number of 
molecules remain the same. Thus : — 1 mole- 
cule of carbon (C) + 1 molecule of oxygen 
(0 2 ) = 1 molecule of C0 2 . Hence the volu- 
metric relation of nitrogen to C0 2 or to a 
mixture of C0 2 + in the combustion pro- 
ducts remains constant and the same as its 
relation to 0. It follows that with any excess 
of air from zero (perfect combustion) to in- 
finity (no combustion) in the burning of pure 
carbon the volumetric percentages of C0 2 + 
when no CO is present will always add up 
to 21. We have seen that: — 

Perfect combustion of a pound of carbon 
requires 11.6 pounds of air, results in 12.6 
pounds of products of combustion, and will 
show 21 per cent C0 2 by volumetric analysis. 
We must now relate the air supply and there- 
fore W d to the volumetric C0 2 of our C0 2 
machine, by means of which together with a 
suitable thermometer in the flue gases we 
must be able to compute our chimney loss. 
Each molecule of C0 2 contains a molecule of 
oxygen and represents the satisfaction of 
chemical combustion requirements. Each 
molecule of free oxygen is of the same weight 
as the oxygen in the C0 2 molecule. Hence 
from our gas analysis we may readily com- 
pute the weight of air in excess of chemical 



318 



PREVENTING POWER-PLANT LOSSES 



g 

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COMBUSTION 319 

requirements, and knowing that one pound 
of carbon requires 11.6 pounds of air for per- 
fect combustion, we may compile a table as 
exhibited on page 318 in which only a few re- 
sults are given by way of illustration. 

Next we must determine the specific heat 
of W d . This depends upon its composition 
which varies from perfect to zero combustion 
as follows: — 

Perfect combustion of one pound carbon re- 
sults in 

3.67 pounds C0 2 X specific heat 0.2170 = . .0.796 
8.93 pounds N X specific heat 0.2438 = . . 2.180 



12.60 total pounds products of combustion. . 2.976 
-T- 12.6 = 0.236 specific heat at perfect combustion. 
Zero combustion results in atmospheric air whose 
specific heat according to Regnault is 0.2375. 

The mean specific heat of the flue gases 
between the extremes of combustion con- 
ditions is therefore (0.236 + 0.2375) -^ 2 
= 0.237 = S. If now we assume various flue 
gas temperatures and a fire-room tempera- 
ture of say 80 degrees F. we shall have all 
the data required to construct an accurate 
set of curves which will show the true rela- 
tion of chimney loss to volumetric percent- 
ages of C0 2 as found in the flue gas, when 
pure carbon is the fuel. -An example is here 
quoted which will illustrate the method for 



320 PREVENTING POWER-PLANT LOSSES 

determination of the curves in Fig. 24 for 
pure carbon. 

Assume T = 400 degrees F. 

t =80 degrees F. 

CO2 = 7 per cent 

O =14 per cent 

CO = per cent 

Substituting* in the formula: — 

L d = W d X S (T — t) 

= 35.8 X 0.237 (400 — 80) 
= 2,715 B.t.u., and the per cent loss 
based on the carbon burned will 
be 

2,715 1Q A 

iT600 = 186percent 



Chimney Loss in the Dry Gases from the 

Combustion or Actual. Bituminous 

Coal. Deduction of a Set of 

Curves for a Selected Coal 

The term combustible in this discussion is 
used according to the definition adopted by 
the American Society Mechanical Engineers, 
e. g., the coal minus ash and moisture. In a 
strict sense this is not a correct definition 
since the fuel contains oxygen which should 
not only not be rated as a combustible but. 
should be rated as a heat deductor. That is, 



COMBUSTION 321 

the oxygen is likely to be in chemical union 
with the carbon before combustion, it may 
possibly be united with the hydrogen though 
not so likely, or it may be chemically com- 
bined with both hydrogen and carbon. (See 
discussion in Chapter XVI on fallacy of Du- 
long's formula.) 

In any event, the oxygen content reduces 
the available heat value of a fuel by com- 
bining with and thus neutralizing a portion 
of its otherwise combustible elements. For 
this reason it is safe to rely for calorific de- 
terminations only upon actual oxygen bomb- 
calorimeter tests. This policy is maintained 
in the following deductions. 

The question of air supply is a separate 
and distinct matter from that of chemical 
arrangement before combustion of the fuel 
constituents, but this however is directly in- 
fluenced by' the amounts of both hydrogen 
and oxygen in the fuel. 

For convenience of computation we shall 
assume that after combustion, the oxygen 
constituent of the coal will be found united 
to its chemical equivalent of hydrogen. This 
oxygen, whether assumed to connect with the 
carbon or with the hydrogen in the final 
analysis, will in either event have exactly the 
same effect in reducing the air theoretically 
required to burn the fuel, and we shall have 



322 PREVENTING POWER-PLANT LOSSES 

to supply enough air to burn the carbon plus 
enough to burn the hydrogen after we have 
deducted that portion of the hydrogen con- 
tent which will be satisfied by the oxygen al- 
ready in the fuel. 

This part of the hydrogen for which we 
must supply air is termed H a in the follow- 
ing treatment, and it is evident that since 
the H a will burn to H 2 which condenses in 
the Orsat machine, the original volume of 
oxygen supplied in air to the fuel will not 
appear as measurable in the Orsat; conse- 
quently the sum of C0 2 + (when no CO 
or hydrocarbons are present) will equal a 
percentage less than 21 depending upon the 
ratio of H a to the carbon content of the fuel. 
The nitrogen of the air supplied to burn the 
H a does appear, without, however, its nor- 
mal complement of oxygen. This adds to the 
nitrogen ratio of the analyzable gas in the 
Orsat, thus reducing the percentage sum of 
C0 2 + 0, zero CO and "zero hydrocarbons 
being assumed as hypothesis in this treat- 
ment. 

As an actual example illustrative of this 
action, in the products of combustion of nat- 
ural gas which has a high hydrogen content 
I have found C0 2 + + (zero CO) equals as 
low as 14 per cent. If we burned pure hydro- 
gen perfectly with no excess air our flue-gas 



COMBUSTION 323 

analysis would show 100 per cent nitrogen 
and zero oxygen. That is, the sum of C0 2 
+ would be zero, while for carbon under 
equally perfect conditions we would have 21 
per cent C0 2 and 79 per cent N. 1 

With this introduction we may now pro- 
ceed to a determination of the dry chimney 
loss as related to C0 2 and flue temperature 
resulting from the combustion of an actual 
sample of bituminous coal which has been 
selected as representative of good Pennsyl- 
vania fuel. In the following deductions it is 
assumed that all the hydrogen in the coal re- 
solves to H 2 in the flue gas, and that neither 
CO nor any hydrocarbons are present. Sul- 
phur is disregarded. ' ' Combustible [ ', it must 
be remembered, is coal minus ash and mois- 
ture. 

In making boiler tests for commercial pur- 
poses where ordinary bituminous coal is 
used, these curves on Fig. 25 will give results 
far closer to accuracy than the usual pure- 
carbon curves. As elsewhere stated, the 
average error resulting from the use of the 
pure-carbon values as applied to this partic- 
ular coal is equal in magnitude to that which 
would be occasioned by a mistake of 100 de- 
grees in the observation of the flue tempera- 
ture. 

1 N is used as the sum of nitrogen plus argon. 



324 



PREVENTING POWER-PLANT LOSSES 



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COMBUSTION" 



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326 PREVENTING POWER-PLANT LOSSES 

From this analysis H = 5 . 54 per cent of the com- 
bustible, or for 1 lb. of combustible we have . 0554 
lb. of hydrogen. The oxygen on same basis = 
0.0715 lb. Per weight of fuel containing 1 lb. of 

0554 
carbon we have ■ Q/fQQ = . 0652 lb. of hydrogen 



0.8489 
l 0.8489 = 



,0.0715 n n0/11 „ 
and ^T^^?i = 0-0841 lb. oxygen. 



ThenH a =H — ~ 

Ha= 0.0652 -^ 

H a = 0.055 1b. 

Now from the atomic weights of H and O we 
know that the burning of H to H 2 = 

2 2 4- 16 = 18 2 ( Hence 1 lb. of H requires 8 lb. 

of O, i.e. ^ =34.8 lb. of air or 457 cu. ft. 1 for 

its combustion. The nitrogen in this amount of air 
will be 0.79 X 457 = 361 cu. ft. of N. 

When 1 lb. of carbon burns to C0 2 we require, as 
before shown, 11.6 lb. of air or 152 cu. ft. From 
these data we may readily deduce that, for perfect 
combustion, 

= 152 X 21 
152 + 361 H a 

Reducing volumes to weights in this formula we 
have : 

p 11.6 X21 , 

P = 11.6 + 26.7 W f ° r PerfeCt 
combustion. 

» Weight of 1 cu. ft. of air = 0.0761 

2 Weight of cu. ft. of N = 0.0738; 0.0738 X 361 = 26.7 



COMBUSTION 327 

The commercial accuracy of this second 
formula for P depends upon the very small 
error (amounting to a maximum of ^ of 1 
per cent) which is introduced owing to the 
slight difference between the weight per cu- 
bic foot of air and of nitrogen. This error 
becomes only a fraction of the percentage 
difference between the above specific den- 
sities of the respective gases since the "H a 
Nitrogen" forms only a small part of the de- 
nominator of the above expression for P, 
and this H a nitrogen becomes relatively less 
as excess air beyond chemical requirements 
is added. 

Substituting in this formula the H a de- 
termined for our selected coal analysis we 
have : — 

p 11.6 X 21 

11.6 + (26.7 X 0.055) 

P = 18.64 

That is to say, the maximum C0 2 percent- 
age obtainable in the burning of this coal will 
be not 21 per cent but 18.64 per cent. 

Now when excess air above chemical re- 
quirements is present the above formula be- 
comes 

11.6X21 
11.6 + 26.7 H a + Ae 

Applying this to our special coal analy- 
sis in which H a — 0.055, and selecting any 



328 PREVENTING POWER-PLANT LOSSES 

per cent of C0 2 — say 10 per cent — as might 
be found on the Orsat we may solve for A e 
as follows: — 

A e = ^jp - 13.07, in which P = 10 

In which case the excess air ( A e ) will be 11.29 
pounds per weight of fuel containing a pound 
of carbon. The percentage excess air over 
that required will be this amount divided by 
it. The air theoretically required will be : — 

A = A c + (A h X H a ), in which 
A c = 11.6 and Ah = 34.8 

Substituting these values: 

A = 11.6 + (34.8 X 0.055) 
A = 13.515 lb. of air per weight of coal con- 
taining 1 lb. of carbon. 

Hence when the C0 2 with this coal is 10 
per cent, the excess air will be 

A e _ 11.29 _ 

A " 13516 " 835 

per cent above the amount theoretically re- 
quired. 

In the construction of the following coal 
curves P was computed in this manner for 
17 different values from 3 per cent to the 
maximum of 18.64 per cent C0 2 , together with 
all the related data given on Fig. 25. These 
may be compared with the pure-carbon 
curves of Fig. 24. 



Mpig^imr : 




















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\f\ctu.aA^itutnhm 

' Jiee Wcj eristic* /^ f<?xt. 




Fig. 25. Actual Bituminous-Co a 



COMBUSTION 329 

The heat carried away up the chimney for 
any percentage of C0 2 per weight of fuel con- 
taining one pound of carbon will be: — 

L d = W d X S (T — t) 

W d = A c + 1 + A e + 0.77 (H a X A h ) 

The last expression only of this formula 
demands explanation as follows: Only the 
nitrogen constituent of the air required to 
oxidize the H a will be found in the dry por- 
tion of the chimney gases, the hydrogen and 
its equivalent oxygen reducing to water. 
This therefore amounts to 77 per cent by 
weight of the required air. 

Substituting the values of our actual coal 
which prevail when C0 2 — 10 per cent as 
per previous deduction, we have: — 

W d = 11.6 + 1 + 11.29 + 0.77 (0.055 X 34.8) 

W d = 25.363 lb. of dry products of combustion 

from the burning of the special coal 

in question when the analysis of flue 

gases shows 10 per cent C0 2 . 

Before applying the formula for L d we 
must determine S which is obtained thus : — 

Perfect chemical combustion of this coal 
produces dry chimney gases from the W d 
formula as below : — 

19RI , rn (3.67 lb. C0 2 3.67 lb. CO2 X 0.2171 = 0.796 

12.6 1b. CO2 J8.93 lb. Nv 

12.60 \ 
0.77 (0.055 X 34.8) = 1.47 lb. N -10.40 lb. N X 0.2442= 2.539 

14.07 1b. 3.335 

1 Specific heat of CO2. 2 Specific heat of N. 



330 PREVENTING POWER-PLANT LOSSES 

3 335 

' n7 = . 237 = specific heat of dry gases when 

combustion is perfect. 

At the opposite extreme, i. e., zero combus- 
tion, the flue gas will be composed entirely 
of air whose specific heat is 0.2375. 

Hence average specific heat of the flue 
gases between the two possible extremes will 
be 0.23725. As the error will be less than 
0.10 per cent we may call S = 0.237. 

To complete our example, assume the tem- 
perature of the fire room t = 80 degrees and 
that of the escaping flue gases 400 degrees F. 
and substitute the values corresponding to 10 
per cent C0 2 in the formula : — 

L d = W d X S (T — t) 
and we have 

L d = 25.363 X 0.237 (400 — 80) 
L d = 1,923 B.t.u. loss per weight of fuel con- 
taining 1 lb. of carbon. 

In this case the carbon constitutes 0.8489 
of the combustible so that the loss per pound 
of combustible burned will be 

L = 0.8489 X L d 
= 1,633 B.t.u. 

We now have a complete analysis together 
with an actual example of the method em- 
ployed to determine the values required for 
the construction of the curves on Fig. 25. It 
may now be seen by a comparison of the pure 



I 



COMBUSTION 331 

carbon and the actual coal curves how great 
an error may occur when the former values 
are used for obtaining" chimney losses in the 
burning of coal. Eoughly speaking, there is 
a difference between the two sets of curves 
amounting to a percentage heat loss corre- 
sponding to about 100 degrees difference in 
flue temperature. 

Detekmination of H a in a Fuel fkom the 
Volumetkic Analysis of the Flue Gases 

For this solution samples of flue gas must 
be obtained which are free from hydrocar- 
bons. 



O m = 21 — (c0 2 + + ^ ) 



F) 



O m = the volumetric percentage of oxygen ab- 
sorbed by the H a in the fuel. 

CO 

The sum of C0 2 + 0-| will equal 

the maximum volumetric percentage of C0 2 
obtainable under perfect combustion with the 
fuel in question. 
The formula : — 

O m 



152 X 



C0 2 + O + ^ 



1 Oxygen when uniting with C to form CO doubles its number of mole- 
cules and hence its volume. 



332 PREVENTING POWER-PLANT LOSSES 

will then be the cubic feet of "measurable 
air" which furnished oxygen for the com- 
bustion of the H a . Only the N of this air will 
appear in the Orsat burette which is there- 
fore the quantity termed "measurable air". 
Now the burning of a pound of H results in 
361 cubic feet of N (as before deduced), hence 

H a = — ■, TT?v\ which simplifies to 



(C0 2 + + ^361 

0^ 

2.37Yc0 2 + + ^] 



O m = 21 — 14 = 7 



To illustrate the use of this formula sup- 
pose our Orsat analysis should give 

C0 2 = 8 1 

0=6 
CO = 
Hydrocarbons = J 

Substituting these values we have: — » 

H » = 2 .37(8 + 6) =0 - 2111b - 

The air required by such a fuel which co- 
incides with tests on natural gas will be : — 

lib. C X 11.6 = 11.60 
0.2111b. H» X 34.8 = 7.35 



Total air required for chemical combus- 
tion of a weight of this fuel contain- 
ing 1 lb. of carbon. 18.95 lb. 



COMBUSTION 333 

Now since we are able to obtain H a from 
the analysis of a proper sample of flue gas, 
we may proceed to determine the approxi- 
mate heating value of the fuel which pro- 
duces these products of combustion as fol- 
lows : — 

Appkoximate B.t.tj. of Combustible fkom 
Flue-gas Analysis 

An amount of fuel containing 1 pound of 
carbon will have a heat value of: — 

1 lb. C @ 14,600 B.t.u. = 14,600 (B.t.u.) 
H a lb. @ 62,000 B.t.u. = 62,000 H a (B.t.u.) 
Total heat = 14,600 + 62,000 H a 

For example, take the case of the flue-gas 
analysis just quoted from which H a was de- 
termined to be 0.211 pound. 

Total heat = 14,600 + 0.211 X 62,000 = 27,682 
B.t.u. in an amount of fuel containing 1 lb. of carbon. 

Based on combustible we have approxi- 
mately — 

27 682 
! + 0.211 = 22 ' 83 ° Rt - U - P6r lb * 

A pound of natural gas from which such 
an analysis might be found would occupy 
about 21.9 cubic feet at atmospheric pressure. 

22,830 



21.9 



= 1,043 B.t.u. per cu. ft. 



334 PREVENTING POWER-PLANT LOSSES 

which is a normally approximate result for 
a natural gas (giving the assumed flue-gas 
analysis) based on actual tests which I have 
made. 

The B.t.u. of the gas thus determined is 
based on that part of the weight of the gas 
which is composed of C and H a only, where- 
as it should, if correct, be based upon the 
total weight of the gas which includes un- 
known quantities of H, 0, N, CO and C0 2 
in various proportions. 

With either coal or gas this flue-gas meth- 
od develops another error common to both 
applications. Since only the H a portion of 
the H is multiplied by the heating value of 
hydrogen, and since the total C is multiplied 
by its heat value, the result will be the same 
as if calculated by Dulong's formula (with 
sulphur disregarded) and will therefore in- 
clude the same error. The cause of this 
error as explained in Chapter XVI is the in- 
correct assumption by Dulong that the oxy- 
gen in the fuel is pre-combined with the hy- 
drogen, which has now been proved to be an 
incorrect hypothesis and leads to a heating 
value lower than would be shown by an ac- 
tual test by bomb calorimeter. 

An example for flue-gas determination of 
the heating value of coal will, however, be 



COMBUSTION 335 

of interest. Take the coal of the composition 
and heat value of our curves on Fig. 25. 

B.t.u. per weight of fuel containing 1 lb. of carbon = 
14,600 + H a x 62,000. 

With zero hydrocarbons in the flue gas this coal 
would show: — 

CO 
C0 2 + O + ^ = 18.64 and 

O m = 21 — 18.6 = 2.4. 

ThenH a= 237 y i86 = 0.055 

We now have: — 

B.t.u. in 1 lb. C = 14,600 

B.t.u. in 0.055 lb. H a (62,000) = 3,410 



B.t.u. in fuel containing 1 lb. C = 18,010 

From the proximate analysis only we 
would not be able to relate this value to com- 
bustible, but since we have in this case the 
ultimate analysis we may do so thus: 

0.8489 X 18,010 B.t.u. = 15,289 B.t.u. per lb. of 

combustible. 

The flue-gas method of approximating fuel 
values is not to be recommended, by reason 
of the inaccuracies referred to as well as 
errors which occur in the Orsat determina- 
tions. The method is of interest principally 
on account of its scientific considerations. 

From formulae thus far deduced we are 
able to calculate within the limits of prac- 



336 PREVENTING POWER-PLANT LOSSES 

tical accuracy the amount of heat carried 
away in the "dry" chimney gases. We have 
now to consider the loss dne to CO or half- 
burned carbon and also the heat carried away 
by the superheated steam resulting from 
moisture and hydrogen in the fuel. 

Loss Due to CO in the Flue Gases 

When there are no hydrocarbons present 
in the flue gases, the B.t.u. loss per weight of 
fuel containing 1 pound of carbon is : — 

L c = 10,150 : " 



P + P c 

in which 

P c = per cent of CO by volume from the Orsat. 
P = per cent of CO2 by volume from the Orsat. 

This follows from the fact that a molecule 
or volume of CO contains the same weight of 
carbon as a molecule or volume of C0 2 , and 
that a pound of carbon in CO when the com- 
bustion is completed to C0 2 develops 10,150 
B.t.u. 

Example 

Flue-gas Analysis — C0 2 = 15 

= 4 

CO = 2 

H.C. = 

Then L c = 10,150 , e 2 , = 1,194 B.t.u. loss per 

15 + Z 

weight of fuel containing 1 lb. of carbon. 



COMBUSTION" 337 

For facilitating this calculation the two 
curves of Fig. 26 have been plotted, one for 
pure carbon and one for the special analysis 
of coal which we have used throughout our 
discussion on combustion. To use either 
curve determine the factor 



Pc + P 

and apply on the ordinate to the upper curve 
for the coal and to the lower curve for car- 
bon. The carbon curve is true for all coals 
when the result is corrected according to the 
percentage of carbon in the combustible, 
which must be had from an ultimate analysis 
of the fuel. 

Wet Chimney Losses 

The remaining chimney' losses constitute 
the heat carried away by the moisture in the 
coal and by the moisture formed by the burn- 
ing of its hydrogen content. These losses 
may preferably be based on combustible. 

If X = pounds of water in the coal per pound of 
combustible, the moisture loss per pound of com-' 
bustible will be: — 

L m = X [(212 — t) + 970.4 + 0.48 (T — 212)] 

The deduction of this formula is self-evi- 
dent if it be considered that the moisture 



•\\--0. 



A7?yldsIJfae S^Mg^Si 



&T:U.Ldsk£i/e to Met 







vj&k 



Fig. 26. Curves of Loss Due to CO in Flue Gases, for Pure Carbon and Actual Bituminous Coal 



338 PREVENTING POWER-PLANT LOSSES 

must first be raised from the fire-room tem- 
perature to 212 degrees (212 — t), then evap- 
orated into steam from and at 212 degrees 
(970.4 = latent heat of steam), and finally 
this steam must be superheated to the tem- 
perature of the chimney gases, 0.48 being the 
specific heat of superheated steam at atmos- 
pheric pressure 0.48 (T — 212). 

Example: — Assume the coal to contain 1/10 lb. 
of moisture per lb. of combustible with t = 80 de- 
grees and T = 400 degrees F. Then 

L m = 0.1[(212 — 80) +970.4 + 0.48 (400 — 212)] 

L m = 119 B.t.u. per lb. of combustible. If the 

combustible has a heating value of 15,000 B.t.u. per 

lb., then the loss due to moisture in the coal is 

119 
., r -_- = 0.794 per cent of the heat of the com- 
15,UUU 

bustible. 

The moisture loss due to the burning of 
hydrogen is obtained by computing the 
amount of water which the hydrogen will 
form and then treating this amount the same 
as water in the foregoing formula. If H x = 
pounds of hydrogen per pound of combusti- 
ble, the pounds of water resulting from this 
hydrogen will be 9 H x per pound of combus- 
tible, and the hydrogen moisture loss will be 

L h =9H x [(212 — 1) + 970.4 + 0.48 (T — 212)] 

Example : — In the coal analysis previously used 
H x = 0.0554 lb. 



COMBUSTION 339 

L h = 9 X 0.0554 [1193] = 595 B.t.u. loss per lb. of 
combustible. 

There is a further wet chimney loss due to 
the moisture in the air, but this is so insig- 
nificant a percentage of the total heat in- 
volved that its elimination from our heat bal- 
ance will not affect the results within the lim- 
its of attainable accuracy. 

In addition to the various chimney losses 
which we have now considered the heat bal- 
ance of a boiler test involves the heat ab- 
sorbed by the boiler 1 and a group of items 
which are usually classified as "unaccounted 
for", and which are generally found by de- 
ducting the sum of the other items from 100 
per cent of the heat of the combustible. 

Heat Balance of a Boilek and Fuknace Test 

1 — Heat absorbed by boiler = heat util- 
ized. 

2 — Heat in dry chimney gases. 

3 — Heat loss due to CO in chimney gases. 

4 — Heat loss due to moisture in fuel. 

5 — Heat loss due to moisture from hydro- 
gen in fuel. 

6 — Heat loss due to unconsumed fuel, drop- 



1 Percentage of heat absorbed by the boiler per lb. of combustible : 
(evaporation from and at 212 degrees per lb. of combustible x 970.4) - 
(heat value of a lb. of the combustible fed to the furnace). 



340 PREVENTING POWER-PLANT LOSSES 

ping through grate to ashpit and fuel re- 
moved through fire door when cleaning. 

7 — Heat contained in hot clinker and ash 
removed from furnace. 

8 — Heat radiated from boiler, furnace and 
setting. 

9 — Heat loss due to unconsumed hydrocar- 
bons and hydrogen and to heating the mois- 
ture in the air. 

The sum of the above values must consti- 
tute 100 per cent of the heat of the combusti- 
ble fed to the furnace. Although items 6 to 9 
inclusive are generally regarded as "unac- 
counted for" and obtained together by sub- 
traction of the sum of the other items from 
100 per cent, it is nevertheless possible to ob- 
tain a fair estimate of items 6 and 7 and 
sometimes of item 8. Item 6 may be obtained 
by taking a fair sample of the total ashes and 
clinker and making a calorific determination 
of its heating value. Then knowing their to- 
tal weight, the loss due to the contained un- 
consumed fuel may be computed. 

Item 7 is practically never recorded and 
credit for its separate inclusion and calcula- 
tion is due to Mr. Albert A. Cary. If the 
temperature of this hot material as it leaves 
the furnace is known (and it can be fairly 
approximated) then its weight multiplied by 



COMBUSTION 341 

its specific heat and by the temperature 'dif- 
ference involved will give the B.t.u. charge- 
able to this item. 

Item 8 — If the boiler is of an internally 
fired type, the radiation loss may be approxi- 
mated by regarding the boiler as a steam ra- 
diator. The total heat that would be given 
off by the bare boiler may thus be computed, 
and if the thermal resistance of its lagging 
be known, a simple calculation in percentage 
will give a rough working figure of the actual 
radiation loss. 



Chapter XIII 
SUEFACE COMBUSTION 

FOE the future improvement of steam- 
boiler and furnace efficiency we may 
expect marked improvement by the employ- 
ment of " surface " or "nameless" combus- 
tion, at least where gaseous fuel is available. 
In fact, the practice has already begun and 
several boilers in England and Germany are 
in operation under this system. This appli- 
cation of the invention has been announced 
only within the last three years. 

As already discussed in Chapter XII on 
Combustion, the one greatest loss in the 
thermal operation of a boiler is the "chim- 
ney loss", which constitutes usually 20 to 30 
per cent of the heat units in the fuel con- 
sumed. This loss is proportional to the 
weight of the hot gases escaping from the 
boiler. 

Their weight is greatly increased in ordi- 
nary practice by the admission to the fur- 
342 



SURFACE COMBUSTION 343 

nace of more air than is actually required for 
the chemical combustion of the fuel constit- 
uents. This excess air must be introduced 
in order to insure contact of the oxygen with 
every particle of the fuel. If absolutely com- 
plete mixing of the air and the gases could 
be effected, this surplus air would not be 
required; but this is not possible to bring 
about even with the more scientific designs of 
common furnaces, with which it is usual to 
find one-third to one-half more air than is 
chemically needed. In poor and ordinary 
furnaces, indifferently operated, the air in 
excess of combustion requirements will range 
from 50 per cent to 400 per cent, with a con- 
sequently heavy chimney loss. 

With surface combustion it is possible to 
furnish an air supply practically within 
chemical requirements. The weight of hot 
gases leaving the boiler is therefore a mini- 
mum for the fuel used and the attendant loss 
is proportionately reduced. 

To Professor Bone of England and Profes- 
sor Charles E. Lucke in the United States is 
attributed the recent development of this 
remarkable form of combustion. Professor 
Lucke has carried on an elaborate series of 
experiments leading to the application of 
surface combustion to various industrial and 
domestic purposes. 



344 PREVENTING POWER-PLANT LOSSES 

Professor Bone, among other devices, has 
developed a boiler which operates on the new 
principle, and the efficiencies combined with 
the capacities which he has obtained have 
exceeded the world's highest boiler-test re- 
sults. He has shown an efficiency as high as 
94.3 per cent, including the heat absorbed 
by a feed- water heater which forms a part of 
his device and is so arranged as to utilize 
some of the heat of the chimney gases. From 
available data it appears that this heater is 
responsible for conserving from 6 to 9 per 
cent of the heat of the fuel, and that the fan 
required for the draft may absorb 3 per cent 
of the steam developed by the boiler. To ar- 
rive at what may be considered average net 
performance of the Bone steam generator, it 
will be fair from various published tests to 
assume an everyday over-all efficiency of 93 
per cent, — deduct 7 for the heater, which 
leaves 86 per cent, and then take 97 per cent 
of this to allow for the steam required to 
drive the fan. This results in a net efficiency 
of 83.4 per cent, and the important fact in 
connection with this result is that it is ob- 
tained on a very small boiler, driven at a tre- 
mendous overload exceeding by many times 
all past performances. 

For instance, one boiler which was fired 
with oil (with arrangement for its gasifica- 



SURFACE COMBUSTION 345 

tion) was 5 feet in diameter and 12 feet long 
with five 9-inch boiler tubes. The total heat- 
ing surface was 123.7 square feet, and it de- 
veloped a total of 89 boiler horse power per 
hour, with an equivalent evaporation of 25 
pounds of water per square foot of heating 
surface per hour. Other units with gas fir- 
ing showed a rate of evaporation as high as 
35 pounds per square foot per hour. Our 
present practice provides an evaporation of 
only from 3 to 6 pounds per square foot of 
surface, 3 being the more common figure. 
Hence the Bone boiler develops on an aver- 
age about seven times the boiler horse -power 
obtainable with other boilers of equal heating 
surface, and it does this at record-breaking 
efficiencies. 

With the above data in mind we may now 
observe that the Bone boiler has developed 
almost six times the boiler horse power gen- 
erated by the great Delray boilers per unit 
of heating surface, and this result was ac- 
complished at an efficiency far higher than 
that of the Delray boilers even when operat- 
ing at their most economical rating. More- 
over, the latter are units of about 2,500 
rated horse power each, whereas the Bone 
boilers were in units which developed from 
50 horse power up to about 350 horse power. 

Other tests on Professor Bone's boiler sub- 



346 



PREVENTING POWER-PLANT LOSSES 



stantiate these results, and an evaporation 
as high as 35 pounds of water per square foot 
of heating surface has been obtained, to- 
gether with an over-all efficiency of 93.8 per 
cent with coal gas as the fuel. 

The operation of surface or nameless com- 
bustion consists in the pre-mixing of the fuel 
gas with almost the exact quantity of air pre- 
scribed by chemical equation, and then burn- 
ing this explosive mixture in a bed of highly 




Courtesy of Steam 

Fig. 27. Dr. Lucre's System of Surface Combustion 

refractory granules which becomes incandes- 
cent at the zone of action. 

As Dr. Lucke explains in his able treatise 
on the subject, it is necessary to introduce 
the gas mixture to the fuel bed at a velocity 
considerably higher than the rate of flame 
propagation. Otherwise the flame will back 
fire into the mixture chamber. Also if the 
gas velocity is not sufficiently reduced after 
its entrance into the combustion section, it 
will blow itself out by mechanically pushing 



SURFACE COMBUSTION 



347 



the burning gas out of the space provided for 
its consumption. 

The former difficulty has been overcome by 
introducing the gas mixture through rela- 
tively long tubes of small diameter so that 
its velocity is always greater than that of 
flame propagation. 

The second trouble, after careful experi- 
menting, was obviated by adjustment of the 




Z'Blo«off\Cock ,'/i 

Fig. 28. Sections of Bone Boiler 



Courtesy of Steam 



shape of the combustion chamber, and the 
size and arrangement of the refractory gran- 
ules, all of which constitute factors govern- 
ing the velocity due both to mechanical and 
thermal expansion of the gases. 

In Professor Bone's boiler here illustrated 
this feature is noted in the small supply tubes 
for the mixture, which in recent designs are 
surrounded by water in the boiler which 



348 PREVENTING POWER-PLANT LOSSES 

keeps their temperature low and thus fur- 
ther reduces the back-firing' tendency. The 
process is known as flameless because the ex- 
plosive mixture employed burns instanta- 
neously (practically speaking) and an incan- 
descent glow only is discernible. In ordi- 
nary combustion a flame is produced because 




Fig. 29. Front View of Bone Boiler 

time is required for the gases and oxygen to 
become mingled into intimate contact with 
each other, and actual burning occurs only 
upon such intimate contact. Consequently 
the process is progressive and slow and 
flame is observed. 

In addition to the direct reduction of chim- 
ney loss by the exact proportioning of air 



SURFACE COMBUSTION 349 

to the fuel made possible by this new pro- 
cess, there are other factors which contribute 
to the superior economies obtained. One of 
these, as may be judged from the illustra- 
tion, is the practical elimination of radiation 
losses. The boiler is internally fired. An- 
other consists in the extremely high temper- 
ature produced inside of the boiler tube 
where the combustion occurs in its bed of 
granules. This condition produces a greatly 
increased rate of heat transference from the 
combustion to the water in the boiler, since 
this rate is proportional to the difference in 
temperature between the hot gases and the 
absorbing body. But a still more important 
factor leading to the rapid heat-transfer ob- 
tained in the tests on the Bone boiler is the 
effect of radiation from the incandescent 
granules inside of each boiler tube. These 
granules attain the same temperature as the 
combustion gases and their "white heat" 
produces a transference more rapid than 
that which is produced by mere contact of 
gases equally hot but low in radiant heat. 

Maximum temperatures are obtainable 
with this process owing to the absence of 
surplus air. The possible temperature of 
combustion may be computed from the heat 
units in the fuel together with the weight and 



350 PREVENTING POWER-PLANT LOSSES 

specific heat of the products of combustion. 
Thus :— 

TT 

T = Wx$' in which 

H = B.t.u. per pound of the fuel. 

W = Total weight of gases resulting from the 
combustion of a pound of the fuel. 

S = Specific heat of the products of combustion. 

T = Degrees F. rise in temperature due to the 
combustion. 

Hence it is clear that by cutting the sup- 
ply of air down to the theoretical minimum 
the products of combustion will also be a 
minimum and the attainable temperature a 
maximum. 

As a matter of interest in this connection 
the records of the development of surface 
combustion show that a large amount of ex- 
perimenting and research were required to 
discover the materials which in the form of 
granules would withstand the extreme tem- 
peratures produced. 

The Bone boiler has been successfully op- 
erated on coal gas, coke-oven gas, and oil; 
plans are made for the consumption of other 
gases and there is no intrinsic reason why 
it should not be successful with all gas fuels. 
It is further stated that experimenting with 
solid fuel has been started. 

It is difficult to predict just what effect 
flameless combustion will have upon our 



SURFACE COMBUSTION 351 

present practice of coal-fired boilers. It was 
long ago proposed to convert coal into gas 
and then fire it nnder the boiler in a suitable 
furnace, with the hope that this method 
would produce decided economies over the 
direct firing of the coal into the boiler fur- 
nace. Of course gas is a nearly ideal form 
of fuel, and offers great advantages over 
solid fuel in that it lends itself to more inti- 
mate mixture with the air for combustion, 
consequently requires a less excess of air 
than coal, is far more readily regulated, and 
is not subject to the necessity and losses of 
furnace cleaning. Therefore its use tends 
toward higher efficiencies than those attend- 
ant upon the use of coal. And all these ad- 
vantages count in its favor when a supply is 
available at prices sufficiently low to compete 
with coal. 

But the conversion of coal into gas with its 
subsequent combustion develops an addition- 
al loss not connected with straight gas-burn- 
ing. This loss attends the gas-producing pro- 
cess, which possesses an individual efficiency 
of its own. Therefore the gas derived from 
the coal contains less heat than the coal it- 
self, so that the over-all efficiency of the pro- 
ducer-gas-fired boiler is at once handicapped 
by the gas-producing losses. And these 
losses have been of sufficient magnitude to 



352 PREVENTING POWER-PLANT LOSSES 

have prevented the attainment of as high 
efficiencies as are at present regularly ob- 
tained in well-designed stoker-fired steam- 
boiler equipments. 

A producer for soft coal suitably designed 
for boiler firing may develop an efficiency of 
90 per cent, providing it be so arranged as 
to make use of the sensible heat in the gases 
from the producer. That is to say, the gases 
which would leave the producer at about 
1,200 degrees F. must not be cooled before 
their combustion under the boiler. It is evi- 
dent, therefore, that even under best condi- 
tions an efficiency loss of 10 per cent must be 
deducted from the best result obtainable with 
straight gas-firing when the gas is made 
in a producer. 

The best present practice in straight gas- 
fired boilers of moderate size indicates an 
efficiency of about 75 per cent, so that if we 
make the gas in a producer, our highest over- 
all efficiency becomes 0.90 X 75 per cent, or 
67.5 per cent. It is apparent, therefore, why 
the producer-gas-fired boiler has not come 
into favor when its efficiency is compared to 
that of good stoker practice of 75 per cent 
efficiency which is readily obtainable with 
even small units. 

Now let us investigate with reference to 
the possible over-all efficiency of a Bone sur- 



SURFACE COMBUSTION . 353 

face-combustion boiler operated on producer 
gas. 

The net efficiency of the Bone boiler may 
be stated as 83.4 per cent, as per our previ- 
ous analysis. Then with a producer effici- 
ency of 90 per cent, as previously discussed, 
the probable maximum over-all efficiency of 
the Bone producer-gas-fired boiler would be 
0.90 X 83.4 = 75.1 per cent. This would rep- 
resent practically no saving over present sto- 
ker-fired boilers of moderate size. As com- 
pared to the large stoker-fired boilers like 
those of the Delray Edison plant, the Bone 
boiler with producer gas would operate at a 
loss as regards fuel consumption. 

It would in truth save a large amount of 
space in the power plant owing to its very 
high steaming capacity per square foot of 
heating surface. Another marked advantage 
would be strongly evident in central-station 
practice where quickly changing and heavy 
peak loads are common ; for each tube of the 
Bone boiler constitutes an individual fur- 
nace in itself. Consequently the variation 
in efficiency is but slight between the ex- 
tremes of minimum and maximum output, 
for as the load increases or decreases an ad- 
ditional furnace or tube is fired or shut off 
completely, so that every such change has no 
effect on the efficiency of combustion and 



354 PREVENTING POWER-PLANT LOSSES 

causes only a very slight change in the effi- 
ciency of the boiler and furnace combined. 

For purposes of comparison with common 
types of boilers the following standards of 
boiler and furnace efficiency may be used as 
representing the most refined practice with 
the respective fuels indicated. 

For oil burning, the boiler tests at the 
plant of the Pacific Light and Power Com- 
pany at Bedondo, California (Trans. A.S.M. 
E. Vol. 33, Collins), gave combined boiler 
and furnace efficiencies ranging from 75.8 
per cent to 83.3 per cent. The average effi- 
ciency of seven tests was 80.47 per cent, cov- 
ering boiler ratings from 72.7 per cent up to 
195.5 per cent of rated capacity. The high- 
est efficiency (83.3 per cent) was obtained at 
109.4 per cent of boiler rating; (builders' 
rating was 604 boiler horse power at about 
10 square feet per horse power). It is to be 
noted that a deduction of 2.4 per cent for 
steam used in atomizing the oil must be made 
to arrive at the highest net efficiency ob- 
tained, which would be 83.3 per cent — 2.4 per 
cent = 80.9 per cent, which may be taken to 
represent the best oil-burning practice. 

For the most refined conditions of firing 
boilers with coal we may take the results ob- 
tained by Dr. Jacobus on the large stoker- 
fired boilers at the Defray station of the De- 



SURFACE COMBUSTION 355 

troit Edison Company (Trans. A.S.M.E. Vol. 
33, Jacobns). These boilers, the largest in 
operation at the present time, each contained 
23,650 square feet of heating surface, giving 
a rated capacity of 2,365 boiler horse power 
at 10 square feet. The highest net efficiency 
obtained was (80.98 — 1.34 1 ) 79.64 per cent 
in a 32-hour test. This was obtained at 98.6 
per cent of boiler rating. 

Isolated tests showing higher efficiencies 
than this have been obtained, some few claim- 
ing 83 or 84 per cent, but about 80 per cent 
combined boiler and furnace efficiency may 
fairly represent the highest results for coal 
burning under actual conditions of practice. 
Even in the above plant when the boilers 
were forced in accordance with good central- 
station practice, the efficiency dropped to be- 
tween 75 and 76 per cent. The capacity of the 
boiler at these low efficiencies was about 200 
per cent of rating, that is approximately 6 
pounds of water were evaporated per square 
foot of heating surface per hour. 

The efficiency of gas firing with small boil- 
ers may reach 75 per cent, and on large boil- 
ers like those of the Detroit Edison Com- 
pany we might expect an efficiency somewhat 
higher than was obtained with coal. A net 



1 1.34 per cent represents the steam used to operate the stoker and the 
draft. 



356 PREVENTING POWER-PLANT LOSSES 

efficiency of 83 per cent would be a good esti- 
mate for natural-gas firing under these larg- 
est of boiler units with suitable conditions. 

The above comparisons are based upon the 
ability to utilize the sensible heat in the gases 
from a producer, and if this is accomplished 
the Bone boiler will be able to show marked 
economies over the average run of small size 
hand-fired boilers, on a basis of competition 
with automatic stokers, and it would cer- 
tainly have the advantage of greatly in- 
creased capacity. 

Possibly a coal furnace may be contrived 
to operate in conjunction with a srnrf ace-com- 
bustion system. Owing to a probable reduc- 
tion of heat losses as compared to a pro- 
ducer, this field of endeavor should prove at- 
tractive to inventors. As before stated, ex- 
periments have been initiated looking toward 
the application of solid fuel to the Bone 
boiler. If success can be attained without 
serious counter losses the greatest field in the 
world will be open to the commercialization 
of this remarkable method of combustion. 

The enormous evaporative capacity of the 
Bone boiler endows it with one great qualifi- 
cation for central-station service, and this 
fact will operate to increase the efforts of 
designers toward the direct and efficient ap- 
plication of coal for this special service. 



Chapter XIV 

NATUKAL GAS AS A BOILER FUEL 

TN" those manufacturing regions where nat- 
ural gas is available at low prices, it is 
also usual to find cheap coals of good quality. 
It is therefore necessary to decide which fuel 
will give the cheapest and most efficient serv- 
ice, and the problem is further complicated 
when the heating of the factory is considered 
in relation to the possible employment of gas 
engines. In every case arising for decision, 
the local operating conditions constitute one 
of the governing factors, and the price, 
heating value and reliability of supply of the 
respective fuels are of equal importance in 
their effect upon the final solution. The cost 
of attendance, initial investment, and other 
financial considerations, have their usual 
bearing upon the ultimate commercial effi- 
ciency; but our present object is to set forth 
the basic information more directly connected 
with the fuel itself, since it is evident that the 
357 



358 



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NATURAL GAS 



359 



other considerations differ widely in accord- 
ance with the local conditions of any given 
case. 

The composition of natural gas varies con- 
siderably, but by way of illustration the fol- 
lowing analysis may be quoted: — 

VOLUMETRIC ANALYSIS OF NATURAL GAS 



CO 

0.50 



H 
2.18 



92.6 



C2H4 
0.31 



CO: 
0.26 1 



N 
3.61 




0.34 



An approximate estimate of the heating 
value of a gas may be obtained by adding to- 
gether the individual heating powers of its 
combustible constituents. Thus for the above 
analysis we would have: — 



Gas 


Per cent of 
Gas by Vol. 


B.t.u. 
per cu. ft. 


B.t.u. 
in Gas 


CO 


0.50 

2.18 

92.60 

0.31 


341 

349 

1,053 

1,675 


1 73 


H 

CH 4 


7.61 
975 07 


C2H4 


5.19 



Total B.t.u. in gas per cu. ft. = 989.60 
When ethane (C 2 H 6 ) is present its heating value 
may be taken at 1,862 per cu. ft. 

The table from Babcock and Wilcox's 
" Steam ", reproduced on page 358, is useful 
in making estimates of this kind. 



360 PREVENTING POWER-PLANT LOSSES 

It is to be noted that the "high" 1 heating 
value of hydrogen is employed in the preced- 
ing data with its consequent effect upon the 
total heat value of the gas in question. 

The calorific power of a gas is best de- 
termined by actual calorimeter test, in which 
the heat of combustion of a measured quan- 
tity is absorbed by water in a properly ar- 
ranged jacket. When the temperature of the 
escaping products of combustion from such 
an apparatus is below the boiling point the 
heat measured will include the high value 
of the hydrogen content. 

The following tests were made under my 
observation on a Sargent gas calorimeter. 
The fuel tested was natural gas at Lima, 
Ohio, supplied from wells in Ashland and 
Medina counties of that State : 



Date of tests June 13, 1914 

Location Lima Gas Works 

Chemist in charge of tests .... Mr. Rodney Lynch 

Room temperature 79 degrees F. 

Test No. 1 

4.89 lb. water raised 19 degrees F. by burning 
0.1 cu. ft. of the gas supplied at 70 degrees F. and 
measured at a pressure of 0.6 inch water gage. 
Barometer 29.6 inches. 

B.t.u. per cu. ft. under these conditions, 966. 

1 See discussion of high heating value in Waste Fuel chapter. 



NATURAL GAS 361 

Test No. 2 

A few minutes later and under the same conditions 
a second test gave B.t.u. per cu. ft. as 1,004. 

Other Tests 

Other tests at the same place made a few days 
previous to the above gave calorific values per cu. ft. 
of 998 B.t.u. and 1,004 B.t.u. respectively. 

For boiler purposes this gas sells accord- 
ing to a sliding scale of prices depending 
upon the rate of consumption, but the aver- 
age price in practice at a boiler plant in 
Lima, Ohio, which I tested was about $0,125 
per 1,000 cubic feet supplied and measured 
at a pressure varying from 8 to 16 ounces 
per square inch. 

In Ashland, Ky., where the natural gas 
was rated by the gas company at 1,145 B.t.u. 
per cubic foot, it was sold for boiler firing 
at the rate of $0.10 per 1,000 cubic feet at 
meter pressure. 

In Hambleton, West Va., the price was the 
same and the gas was rated at 1,123 B.t.u. 
per cubic foot. 

The efficiency of natural gas as used for 
steam generation may be deduced from seven 
boiler tests which I made at the above named 
places. 

Under actual conditions of firing a boiler 
horse-power hour was obtained from an av- 



362 PREVENTING POWER-PLANT LOSSES 

erage consumption of 40.4 cubic feet of gas 
at the metered pressure, the minimum being 
37.3 cubic feet and the maximum 43.8 cubic 
feet. 

With a good burner and a clean boiler 
there is no difficulty in obtaining combined 
boiler and furnace efficiencies from 70 to 74 
per cent. Hence as compared to ordinary 
hand firing of soft coal, which gives an effi- 
ciency of 60 to 65 per cent, the gas shows to 
advantage in cost of evaporation, providing 
the same number of heat units may be pur- 
chased for a dollar. If opinion must be 
formed without any actual tests as to which 
fuel will produce the cheaper steam, it is best 
to base the comparison in case of hand firing 
on 63 per cent efficiency for the soft coal and 
73 per cent for the gas. If on the other hand, 
a good stoker furnace were to be considered 
for the coal, it is safe to figure on equal effi- 
ciencies for both the coal and the gas in com- 
puting the fuel cost of evaporating 1,000 
pounds of water. In practice these actually 
determined costs of evaporation with natural 
gas in the places mentioned ranged from 
$0.0926 to $0.1582. 

The gas equivalent of coal in any locality 
depends upon the heat value of the coal and 
upon the heat value of a cubic foot of gas at 
the metered pressure. 



NATURAL GAS 363 

The heating power of natural gas should 
be based on a unit volume at atmospheric 
pressure and a stated temperature usually 32 
or 62 degrees F. 

The most normal standard for general use 
is a temperature of 62 degrees and an at- 
mospheric pressure of 14.7 pounds per 
square inch. The following formula is based 
on these values : — 

Vo = I -lAjrp I V, which simplifies to 

Vo = ( 35 -y V \ V, in which 

Vo = the standardized volume in cu. ft. 

p = absolute pressure at which the gas was 

metered in lb. per sq. in. 
T = absolute temperature F. at which the gas 

was metered. 
V = volume in cu. ft. of the gas as metered. 

Calorific tests to determine the heating 
value of the gas are likely to be made at a 
temperature of about 62 degrees. This tem- 
perature standard is therefore more rational 
since the calorimeter results require less ad- 
justment. The same argument holds good 
for boiler testing, since the gas will be me- 
tered at a temperature nearer 62 than 32. In 
any event, for commercial comparisons of 
the fuel values of gas and coal it is essen- 
tial that the average pressure and tempera- 



364 PREVENTING POWER-PLANT LOSSES 

ture of the gas at the meter be known in 
order to arrive at a determination of the trne 
heating valne of the fnel as purchased at the 
meter. 

The pressure factor is the more important, 
as may be seen from the following example 
in which the 62-degree standard is assumed. 
Thus if the gas is metered at one pound pres- 
sure, i. e., 15.7 pounds absolute, the heating 
value of a cubic foot will be nearly 7 per cent 
greater than the same quantity at atmos- 
pheric pressure, whereas a temperature rise 
even as great as 20 degrees will lower the 
heating value to the boilers by only 3.7 per 
cent. 

If we desire to learn the gas equivalent of 
coal for any set of conditions the following 
example will serve as illustration of the 
method to be used. 

The gas available has a heating value of 
1,000 B.t.u. per cubic foot at atmospheric 
pressure, and a temperature of 62 degrees F. 
It is supplied at an average pressure of 1 
pound per square inch at the meter and its 
average temperature is taken at 65 degrees. 
Its price is 10 cents per 1,000 cubic feet, as 
metered at the boiler room. 

Applying the formula we have : — 

VO = ( 3544 52 X 1 157 ) V = 1068V - 



NATURAL GAS 365 

That is to say, a cubic foot as metered con- 
tains 1.068 times the weight or B.t.u. in a 
standard cubic foot. Hence a cubic foot as 
metered will contain 1.068 X 1,000 B.t.u. = 
1,068 B.t.u. A thousand cubic feet as me- 
tered will therefore contain 1,000 X 1,068 = 
1,068,000 B.t.u. at a cost of 10 cents. For 
$1.00 we may purchase 10,680,000 B.t.u. in 
natural gas. 

Now supposing the delivered price of coal 
in this locality is $2.00 per ton of 2,000 
pounds having a calorific power of 13,500 
B.t.u. after deducting 5 per cent of its B.t.u. 
per pound to allow for contained moisture. 
Then $1.00 ivill purchase in coal 13,500,000 
B.t.u. and in natural gas 10,680,000 B.t.u. 
That is, with equal boiler and furnace effi- 
ciencies (assuming good stoker conditions in 
the case of coal) the coal would generate 

13,500,000 - 10,680,000 

10,680,000 ' ° r 

26.4 per cent more steam for the same ex- 
pense for fuel. (Labor and investment com- 
parisons must be made separately as condi- 
tions may demand.) 

Without regard to prices, 1,000 cubic feet 
of natural gas under the above assumptions 
(which are characteristic of many gas re- 
gions) will have a heating value equal to that 



366 PREVENTING POWER-PLANT LOSSES 

of 79.1 pounds of 13,500 net B.t.n. coal. With 
natural gas and coal of the above specifica- 
tions, coal at $2.53 per ton of 2,000 pounds 
would equal gas at $0.10 per 1,000 cubic feet. 

When gas is compared to coal for boiler 
purposes no allowance need be made for dif- 
ferent boiler and furnace efficiencies when the 
coal is stoker fired and the gas is used in a 
good furnace. When the comparison refers 
to ordinary hand-firing of soft coal, how- 
ever, the calculation must allow for a lower 
efficiency of the coal. A common pair of 
figures would be 63 per cent efficiency for the 
coal and 73 per cent for the gas. Both fuels 
may burn at efficiencies either higher or lower 
than these, and the local conditions should 
be carefully investigated, preferably by ac- 
tual test in order to insure a correct com- 
parison. 

Burners and furnaces for natural gas vary 
considerably in their design, and some of the 
home-made ones in my tests gave as good re- 
sults as some of the patented ones. 

The principal requirements for the effi- 
cient combustion of gas are as follows : 

1. A thorough mixture of the gas with 
the required air. This is accomplished in 
three ways : (a) the burner proper may be so 
designed as to cause an excellent mixing ac- 
tion before the fuel enters the furnace; (b) 



% NAT URAL GAS 367 

the mixing action may take place in the fur- 
nace itself, and it is usually augmented by 
baffles or checkerwork of firebrick which 
break up the currents of flow; (c) the cross- 
section of the furnace may be made large 
enough to compel a slow passage of the gas 
and air, thus providing time for their nat- 
ural diffusion. 

2. The maintenance of high temperature, 
which is accomplished by the impingement 
of the burning gas against hot brickwork, by 
its combustion within a firebrick furnace, and 
by retaining the gas in the furnace or com- 
bustion chamber until its combustion is prac- 
tically completed. 

3. Correct air supply. This also directly 
affects the second or temperature require- 
ment. It may best be regulated both by ac- 
tual testing of evaporative results and by 
making flue-gas analyses of the products of 
combustion. A rough and ready method 
consists in reducing the damper opening un- 
til smoke appears, and then opening the 
damper just wide enough to give a clear 
stack ; but this method is not infallible, since 
it will not discover faults in the mixing ac- 
tion of the furnace as will tests by flue-gas 
analysis. 

With a horizontal tubular boiler it is easier 
to furnish ample combustion space, because 



368 PREVENTING POWER-PLANT LOSSES ■ 

of the long passage underneath, whereas 
with a water-tube boiler there is great dan- 
ger that the gas and air may pass between 
the tubes before their combustion is effected. 
This bad result is guarded against by the in- 
terposition of checkerwork or baffles or by 
deepening the furnace. 

A very light draft (that is, one of small 
pressure) gives the best results with nat- 
ural gas, so that a low stack may be used 
successfully. One reason for this is that the 
resistance due to draft passage through a 
grate and a bed of fuel is eliminated, and this 
resistance constitutes roughly one-half of the 
entire drop in draft intensity through the 
complete boiler setting. There is usually suf- 
ficient pressure at the gas burners not only 
to impel the gas into the furnace, but also to 
cause an inspiratory action which tends to 
draw in to the furnace the air for combustion, 
so that, roughly speaking, the chimney need 
overcome only that part of the resistance 
which is offered by the passages through the 
boiler and flues. I have obtained 74 per cent 
efficiency on a horizontal tubular boiler op- 
erating at 90 per cent over its rating (at 12 
square feet per horse power) with an aver- 
age draft intensity of 0.2 inches water-gage 
measured between the damper and the boiler. 
It is best of course to provide more draft 



NATURAL GAS 369 

than this in case of necessity such as might 
be caused by varying gas pressure, design 
of boiler and burners, pressure of gas at 
burners, and type of boiler. . 

The burners are usually inserted in the 
boiler front just above the coal grate, which 




Fig. 30. The Kirkwood Burner 

is bricked off, although with certain types of 
boilers like the vertical water-tube variety, 
the gas is fired through the front of Dutch- 
oven furnaces. 

The burners themselves vary considerably 
in design. Two very good designs which I 
have tested are here illustrated. The Kirk- 
wood system provides one burner for every 



370 



PREVENTING POWER-PLANT LOSSES 




NATURAL GAS 371 

20 boiler horse power. The air enters 
through the large circular opening of each 
burner and the gas at a pressure of (pref- 
erably) about 8 ounces is fed to the annular 



£ 



Fig. 32. Typical Setting of Kirkwood Burners under 
100 Horse-power Boiler 

space which surrounds the air duct, and finds 
its way into the air tube through numerous 
communicating small holes which direct the 
gas into a corkscrew or whirling motion. 
This action aids the desired intimate mixing 
of the gas with the air. Both air and gas 



372 



PREVENTING POWER-PLANT LOSSES 




NATURAL GAS 373 

are separately controlled, and in operation 
are so adjusted as to provide complete com- 
bustion at the mouth of each individual tube. 
The most efficient regulation of the fire is 
obtained by completely shutting off or fully 
opening up one of these burner units. In 
this manner the ratio of air to fuel remains 
constant at all different ratings of the boiler. 




Fig. 34. Gwynn Gas Burner 

The Gwynn burner, as may be seen from 
the cuts, is constructed on the same general 
principles of operation just described. 

Usual methods of furnace construction for 
gas burning are shown herewith as applied 
to horizontal tubular and water-tube boiler 
practise. 

The bunsen type of burner is easily con- 
structed from two pipes of different size ; the 
larger is for the air and receives the gas at 
the centre of its opening. The inner end of 
this larger pipe or nipple leads just through 



374 PREVENTING POWER-PLANT LOSSES 

the boiler front. It is important that such 
burners be provided with individual covers 
for shutting off the air when the gas is 
stopped. Both good and bad results are ob- 
tained with these burners, depending prin- 
cipally upon the design and regulation of the 
furnace. One of my best and one of my worst 
tests were made on boilers supplied with 
home-made burners. 




Fig. 35. Sectional View op Gwynn Gas Burner 

Analyses of the products of combustion of 
natural gas provide a striking contrast with 
the results from coal. With pure carbon the 
volumetric percentages of C0 2 and will add 
up to 21 when there is no CO present in the 
burner gases. With hard coal this total of 
21 per cent is approximated. With bitumi- 
nous coal the total will generally run from 
18 to 20 when no CO is found. With the com- 
bustion of natural gas, of the compositions 
prevailing in my commercial tests on this 



NATURAL GAS 375 

fuel, the total of C0 2 + when no CO was 
present has varied from about 13 to 16 per 
cent. 

The reason for this dropping off of "total 
volume" from hard coal to soft, and again 
from soft coal to natural gas 1 , is the greater 
proportion of hydrogen in the latter fuels, 
the gas containing the most. The burning 
of hydrogen results in the generation of su- 
perheated steam, thus H 2 + = H 2 0, and 
this steam condenses to water in the Orsat 
apparatus or before reaching it, so that its 
volume as a combustion product is not meas- 
urable in the analysis. Hence the greater 
the hydrogen constituent of a fuel, the less 
will be the sum of the gases determined by 
the usual Orsat type of gas machine. 

From the above it may be properly con- 
cluded that with the same fractional sur- 
plus of air supplied to the combustion, the 
percentage of C0 2 from the burning of nat- 
ural gas will be much lower than from the 
burning of coal, and this is the case in prac- 
tice. In fact the best efficiencies have been 
obtained with natural gas when the average 
C0 2 was between 8 and 9 per cent, while in 
soft-coal burning with equal efficiencies 12 to 
14 per cent of C0 2 would be expected. 

1 See Chapter XII with actual example and calculation on natural 
gas. 



376 



PREVENTING POWER-PLANT LOSSES 






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NATURAL GAS 



379 



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384 PREVENTING POWER-PLANT LOSSES 

The preceding records of five boiler tests 
which I made for commercial purposes are 
given to show results obtained under varying 
circumstances. These represent the opera- 
tion of two horizontal tubular and one water- 
tube boiler, under different conditions as in- 
dicated by the observations on kind of burn- 
ers, draft, boiler output, flue-gas analyses, 
etc. 



Chapter XV 
NATURAL GAS (Continued) 

GAS ENGINE VERSUS STEAM ENGINE 

TN the natural-gas regions manufacturers 
A must determine whether this fuel will give 
the greater commercial efficiency when used 
directly in a gas engine or when applied to a 
boiler and steam engine. 

The conditions of the problem will abso- 
lutely govern the results, but first let us com- 
pare the several over-all thermal efficiencies 
which are usually found in factory work, re- 
membering that other things being equal the 
cost of power is inversely proportional to 
thermal efficiency. 

Plant No. 1 
Natural-gas-fired boilers. Steam engine, simple 
non-condensing. Exhaust steam wasted. 

Boiler and furnace efficiency = 73 per cent 
Steam-engine efficiency = 7 per cent 

Over-all efficiency = 5.11 per cent 

Plant No. 2 
Natural-gas-fired boilers. Steam engine, com- 
pound condensing or turbine. No exhaust-steam 
heating. 

385 



386 PREVENTING POWER-PLANT LOSSES 

Plant No. 2 — {Continued) 

Boiler and furnace efficiency = 73 per cent 
Steam-engine efficiency =15 per cent 

Over-all efficiency = 10 . 95 per cent 

Plant No. 3 

Gas engine using natural gas. No by-product 
heat reclaimed. 

Engine efficiency = 20 per cent 

Over-all efficiency *= 20 per cent 

Plant No. 4 

Natural-gas-fired boilers. Steam engine simple 
non-condensing. Exhaust steam efficiently utilized. 

Boiler and furnace efficiency = 73 per cent 
Engine efficiency l = 80 per cent 

Over-all efficiency = 58 . 4 per cent 

It must be understood that the above as- 
sumed efficiencies will individually vary with 
excellence of equipment and operation, and 
consequently they must be regarded only as 
approximately typical of the designs of plant 
which they respectively represent. Bearing 
this precaution in mind, we may state that 
for the same gas consumption, a plant of the 
design of No. 4 will give nearly three times 
as much value as the most efficient of the 
others ; that the gas engine of plant No. 3 will 
develop about four times as much energy 
as plant No. 1 and nearly twice the energy 
of plant No. 2 for the same amount of gas. 

1 See Utilization of Exhaust Steam, Chapters II and V. 



NATURAL GAS 387 

But in actual practice the price charged 
for natural gas when used in a gas engine is 
much higher than when fired under a boiler. 
For example, in a recent case in Ohio the gas 
for boiler purposes cost $0,125 and for gas 
engines about $0.28 per 1,000 cubic feet. 
Hence with these prices, plant No. 1 would 
pay 0.125 -=- 0.280, or nearly 45 per cent as 
much for a given amount of fuel, but this fuel 
would generate only 25% per cent as much 
energy as it would develop if used in plant 
No. 3. Therefore the commercial efficiency 
of plant No. 1 would be far below that of the 
gas-engine plant in this instance. 

In order to run the simple non-condens- 
ing engine of plant No. 1 at the same charge 
for gas as plant No. 3, the gas for boiler pur- 
poses would have to cost 5.11 -f- 20, or only 
about 25% per cent as much as when burned 
directly in a gas engine. That is to say, the 
prices of gas must be inversely proportional 
to the over-all thermal efficiencies of the dif- 
ferent plants to make their commercial effi- 
ciencies equal. 

The above classification shows at a glance 
very closely what may be expected from the 
use of natural gas in the different types of 
plants indicated where their respective effi- 
ciencies agree with those indicated. 

From the above classification we may se- 



388 PREVENTING POWER-PLANT LOSSES 

lect the general type of plant which will give 
the highest commercial efficiency with nat- 
ural gas when the two prices of gas are 
known, provided we alter the individual effi- 
ciencies given as necessity may demand. 

There are of course plants of mixed de- 
sign which may combine certain features of 
all four types. Also an existing plant of one 
of the types quoted may have, as previously 
indicated, an over-all thermal efficiency quite 
different from the efficiency designated for 
that plant in the foregoing classification. 
Consequently the certain way of arriving at 
best results for a given case is to base all 
computations on actual tests made upon both 
present and contemplated equipments. In 
the first place, such a method will have the 
advantage of discovering correctible losses 
in the existing conditions. Thus sometimes 
the efficiency of the old plant may be so im- 
proved at slight expense as to preclude the 
economy of the contemplated and more ex- 
pensive change. For instance, if in a plant 
like No. 1 or No. 2 a sufficient use for exhaust 
steam can be made feasible, it would not pay 
to substitute a gas-engine plant like No. 3. 
An investigation would prove this and other 
matters connected with future economies. 

The following example illustrates the test 
method in the solution of a problem. 



NATURAL GAS 389 

Question: Will it pay to substitute a gas 
engine for a 100-kilowatt Corliss steam en- 
gine now running and wasting all of its ex- 
haust steam, none of which can be used un- 
der existing conditions! The steam engine 
under test consumed an average of 28 pounds 
of steam per indicated horse-power hour, 
which average figure cannot be much im- 
proved under the imposed conditions of steam 
and load. The boiler supplying the engine 
shows under test an evaporation of 0.85 
pounds of water per cubic foot of gas under 
actual commercial conditions. It is found to 
be developing an efficiency of 74 per cent 
which cannot be much improved for a 150 
horse-power boiler under everyday working 
conditions. 

Now from actual tests on factory gas en- 
gines of this capacity (see table of some of 
author's tests on factory gas engines) we 
know that we may expect a brake horse- 
power hour for a consumption of 12 cubic 
feet of gas under working conditions on the 
best design of engine. The prices of gas are 
10 cents and 30 cents for boiler and gas- 
engine consumption respectively. The effi- 
ciency of the electric generator is 94 per 
cent. 

We may then compute as shown in the cal- 
culation on the following page: — 



390 



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NATURAL GAS 393 

Under the conditions of prices and opera- 
tion shown in the computation on page 390, 
the fuel for either the steam engine or the 
gas engine would cost almost the same 
amount, with a trifle of difference in favor of 
the steam engine. 



Chapter XVI 

THE ECONOMIC COMBUSTION OF WASTE 
FUELS 

THE term " waste fuel" as used in this 
chapter means any combustible mate- 
rial which is not ordinarily included in the 
list of commercially marketable fuels. 

Among the marketable fuels would be in- 
cluded bituminous and anthracite coals of 
the various grades and compositions; crude 
oil, fuel oil and the petroleum distillates, such 
as kerosene, gasoline and naphtha; the alco- 
hols, grain (ethyl) and wood (methyl) ; some 
kinds and forms of wood ; charcoal and coke ; 
certain gases, such as natural gas, water 
gas, coal gas and producer gas ; also peat and 
lignites. 

As waste fuels would be classified the fol- 
lowing: sawdust, shavings, scraps, edgings; 
tan bark, wood-extract chips; bagasse or 
spent sugar cane; anthracite coal passing 
through 3/32-inch mesh, known as culm ; coke 
394 



WASTE FUELS 395 

braize, and city refuse. It will be noticed 
that these waste fuels (with the exception of 
culm and city refuse) "are all by-products of 
manufacturing industries, and even culm 
might be so considered. City refuse is really 
a by-product of the various domestic indus- 
tries inseparable from community living. So 
that the definition of waste fuel in a broad 
sense might be termed any combustible ma- 
terial resulting as a by-product of manufac- 
ture. 

There are two distinct classes of waste 
fuels — " auto-combustibles, " which maintain 
their own combustion after ignition, and com- 
bustibles which will not burn without the ad- 
dition of heat from an outside source or 
without mixture with an auto-combustible. 
This second class may be termed for conven- 
ience " semi-combustibles. ' ' With the im- 
provement of furnaces for the handling of 
waste fuels, certain materials which w T ere 
previously considered only semi-combustible 
have joined the list of auto-combustibles. 

The semi-combustibles resist self-ignition 
principally by reason of excessive moisture, 
ash, and refuse, and by physical structure 
tending either to resist the passage of the 
draft or to form large openings in the fuel 
bed which admit a great excess of air beyond 
that required for combustion, thus lowering 



396 PREVENTING POWER-PLANT LOSSES 

the furnace temperature and efficiency con- 
ditions. 

A certain amount of heat must be given 
back to a substance in order to maintain its 
combustion. This is illustrated very nicely 
by removing suddenly the flame from a can- 
dle, which can be done either by a quick 
movement of air such as a puff of wind or by 
removing the air by smothering. The result 
is the same. The candle had been absorbing 
a part of the heat developed in the flame. As 
soon as this was no longer possible on ac- 
count of the removing of the flame, combus- 
tion ceased, and to start it once more suffi- 
cient heat must be applied to secure the com- 
bustion temperature. 

As a practical example, it is necessary, ac- 
cording to Stromeyer, to raise the tempera- 
ture of lump coal to approximately 600 de- 
grees Fahrenheit before ignition with the 
oxygen can take place. This figure multi- 
plied by the specific heat of the coal would 
give the number of heat units required to be 
given by the fire to each pound of coal 
burned. 

If what may be called the gross calorific 
value of a substance is actually less than the 
heat required to maintain its combustion, it 
is manifestly obvious that such a substance 
cannot be auto-combustible, and such sub- 



WASTE FUELS 397 

stances, even when made combustible by ap- 
plication of heat from an outside source, will 
not give up any available heat for useful pur- 
poses since the amount produced is less than 
that actually required for maintaining their 
own combustion. 

In the gasification of carbohydrates (i. e., 
fuels containing carbon, hydrogen and oxy- 
gen), which precedes combustion, a rather 
complicated chemical reaction takes place 
which either develops or absorbs heat. If 
the former, the reaction is known as exother- 
mic ; if the latter, endothermic. An exother- 
mic reaction tends automatically to promote 
combustion, and the endothermic to retard. 
But since either condition is algebraically in- 
cluded in the calorific value of a substance, 
these interesting phenomena do not require 
separate consideration for the present pur- 
pose. 

The amount of heat required to maintain 
combustion of a Substance depends upon va- 
rious factors. The first stage of combustion 
is gasification; therefore the heat required 
to gasify must be supplied in order to main- 
tain combustion, and it is evident that the 
amount so required will depend upon the re- 
sistance to be overcome in order to gasify the 
substance. Moisture is a serious detriment 
to combustion, for the reason that it must be 



398 PREVENTING POWER-PLANT LOSSES 

gasified, requiring in addition to the sensible 
heat the application of 970 B.t.u. for each 
pound that must be removed, which heat 
must be obtained from the total heat value of 
the combustible. 

Such substances as have been designated 
as semi-combustibles intrinsically possess a 
greater number of heat units than are theo-. 
retically required to maintain the combus- 
tion of said substances. This class of com- 
bustibles, among which are included certain 
kinds of refuse, wet chestnut chips, etc., may 
become actually auto-combustible, depending 
upon the efficiency of the conditions with 
which they are surrounded, such as hot sur- 
faces, heated air supply, large combustion 
space, continuous feeding of the fuel and 
removal of ash, etc. 

Thus some of these waste fuels will refuse 
to burn without the addition of coal or other 
outside fuel in most furnaces, and yet in a 
furnace which provides nearly perfect condi- 
tions for combustion, these same substances 
will burn and give off a large amount of 
available heat. As an illustration — wet spent 
chestnut chips until recent years would not 
burn unless they were supplied with addi- 
tional heat from coal either by mixing or 
otherwise. Still another instance would be 
some kinds of city refuse, which when ordi- 



WASTE FUELS 399 

narily treated refused to burn unless sup- 
plied with heat from a separate source. By 
the scientific design of furnaces and by care- 
ful homogeneous mixing of the various ma- 
terials of this refuse, it is now burned with- 
out additional heat and at an efficiency high 
enough to make steam which can be used to 
operate the plant. These furnaces will be 
described in following pages. 

Other fuels can be made more efficient by 
simply reducing the amount of moisture they 
contain without altering the design of fur- 
nace equipment. Special tests on moist fuels 
show close agreement between theory and 
practice in this respect. 1 

In conclusion of the above aspect of the 
problem, it can be said that the more nearly 
perfect are the means for burning the sub- 
stance in question, the more nearly will semi- 
combustibles approach the state of auto-com- 
bustion. 

Perhaps the most important of waste fuels 
in the United States has been spent tan bark. 
A rough estimate would indicate that this 
material generated a few years ago an 
amount of steam that would have otherwise 
required the yearly consumption of about 
2,000,000 tons of high-grade coal. Yet this 



1 See author's paper, American Society of Mechanical Engineers, "Tan 
Bark as a Boiler Fuel." 



400 PREVENTING POWER-PLANT LOSSES 

valuable fuel was at one time considered a 
mere detriment and an expense to the leather 
industry. It was disposed of by dumping 
it into rivers, filling in waste ground, and by 
making roads with it, often necessitating the 
paying out of large sums for its disposition. 
This strikingly illustrates a case of how the 
improvement of a furnace converted a hith- 
erto supposed incombustible into a valuable 
waste fuel of the auto-combustible class, and 
shows how an enormous waste was converted 
into an equally great economy. 

An interesting example of the promotion 
of a previously considered semi-combustible 
to the list of auto-combustibles was the case 
of chestnut-wood extract chips. This fuel is 
the by-product resulting from the manufac- 
ture of a tanning agent largely and increas- 
ingly used in the manufacture of leather. 
Chestnut wood is first fed into chippers, then 
through disintegrators which reduce it to a 
finely divided state with particles about the 
size of No. 2 buckwheat coal. After being 
subjected for about a week to a hot-water 
treatment which extracts most of the avail- 
able tannins, the spent chips are conveyed 
into the fireroom for burning. In this state 
they contain from 60 per cent to 65 per cent 
of moisture, and a dry pound shows about 
8,400 B.t.u. That is about 1,100 B.t.u. less 



WASTE FUELS 401 

than spent tan, which contains the same per- 
centage of moisture. Ten per cent of this 
moisture can be removed by means of special 
presses for the purpose. 

Ever since the institution of chestnut ex- 
tract, the resulting chips were burned only 
by making with them a rich mixture of coal, 
or by maintaining a separate coal fire whose 
flames passed over the chips for the purpose 
of drying and igniting them. 

In connection with this problem I designed 
a special type of furnace suited to the char- 
acteristics of this fuel. It then became possi- 
ble to burn it without the addition, or mix- 
ture, of coal. In one of the foremost extract 
plants, this resulted in a great saving of coal 
and immediately advanced spent chestnut- 
extract chips to the ranks of auto-combus- 
tibles. 

The matter of high efficiency in the utiliza- 
tion of by-product or waste fuels is just as 
important in establishments where such ma- 
terial furnishes only a part of their fuel sup- 
ply as in plants that are operated entirely on 
commercial fuels, such as coal or gas. For 
in the first place, a highly efficient plant 
may be enabled to run entirely upon its by- 
product fuel material, whereas (as in my own 
experience) another plant in the same in- 
dustry, of the same output capacity, but with 



402 PREVENTING POWER-PLANT LOSSES 

inefficient combustion equipment, may re- 
quire additional fuel to the extent of many 
thousands of dollars a year. Furthermore, 
in a plant which depends partly on waste 
fuel supplemented by purchased fuel, any 
percentage saving that results from the im- 
provement of the combustion system will 
produce an actual saving in the purchased 
fuel of this percentage multiplied by the frac- 
tion which represents the ratio of the total 
heating value of the combined fuel to the 
heating value of the purchased fuel. 

For example, consider the case of a plant 
which consumes the equivalent of 100 tons 
of coal a day, of which heating value the. pur- 
chased fuel constitutes one-third (yi). Now 
if the efficiency of the furnace equipment is 
so improved as to produce the same steam or 
power for ten (10) per cent less fuel (or heat 
units), since the consumption of waste fuel 
still remains the same, the entire saving of 
fuel is effected from the purchased supply. 
In this case, therefore, in which a total sav- 
ing of 10 per cent has been made, the expense 
of purchased fuel has been reduced not only 
10 per cent, but (3 --^- 1) X 10 = 30 per cent. 
This simple arithmetical truth is but little 
if at all recognized by owners whose plants 
are operated on mixed fuels, or their com- 
bustion would receive far more attention. 



WASTE FUELS 403 

The above considerations make the study 
of waste fuels and their efficient combustion 
most important. 

Principles Involved 

With waste fuels, in common with other 
fuels burned for boiler purposes, efficiency 
depends upon- three conditions: 

1. High temperature. 

2. Correct amount of air supply, and 

3. Complete mixture of this air with the 
fuel gases. 

The great difference in the burning of 
waste fuels is not in the requirements for 
combustion, but in the difficulty of meeting 
these same requirements. 

In the first place, temperature of combus- 
tion depends upon two factors : 

a. The calorific value of the fuel, and 

b. The amount of heat absorbed by its 
resulting products of combustion. 

The temperature of combustion is directly 
proportional to the first and inversely pro- 
portional to the latter. The calorific value 
of waste fuel is generally comparatively low ; 
hence the first difficulty in obtaining high 
temperature. 

A larger percentage of moisture results in 
a greater weight of products of combustion, 



404 PREVENTING POWER-PLANT LOSSES 

and these products have a higher specific 
heat than flue gases, and, what is far more 
serious, involve also the latent heat of steam. 
Thus again the moist waste fuel presents 
further difficulty towards securing the first 
requirement for good combustion. In con- 
nection with this same requirement, the high- 
est constant temperature can be maintained 
only when the fuel is introduced at the same 
rate at which combustion is taking place. 
With coal this is both possible and practic- 
able, notably with certain forms of automatic 
stokers, and can even be approximated with 
skilful hand firing. But with waste fuels, 
special study and often much skill are re- 
quired, owing to the great bulk and peculiar 
form of the material to be handled. 

Again, with reference to the second re- 
quirement, that of correct air supply, waste 
fuel requires different treatment from coal. 
In the first place the weight of air theoret- 
ically required to oxidize or burn completely 
a pound of the fuel, depends upon its chem- 
ical composition. Thus carbon requires oxy- 
gen equal to 2 2/3 times its own weight, and 
hydrogen 8 times its own weight. 

Beyond this theoretical air supply, an ex- 
cess of from 50 to 250 per cent must be pro- 
vided, according to the fuel in question and 
the design of the furnace. The latter should 



WASTE FUELS 405 

be so constructed as to provide a thorough 
mixing of the air with the fuel gases at a high 
temperature, in order to reduce to a mini- 
mum the loss due to the great excess of air 
otherwise required. Still another difficulty 
has to be met in this connection. Certain 
waste fuels have a strong tendency to form 
blow holes, due either to clinker or lightness 
of the particles, in which latter case they are 
ripped from the grates and carried unburned 
through the flues and up the stack as waste. 
In either case, the blow holes lower the effi- 
ciency by admitting excessive amounts of 
cold air to the furnace, which reduce its tem- 
perature seriously. The opposite trouble oc- 
curs when the grates are too heavily loaded 
with a moist fuel that packs and checks the 
flow of the draft. Thus special construction 
and skill are required to overcome these diffi- 
culties, the occurrence of either one of which 
will utterly ruin the efficiency of the fire. 

Another set of difficulties has to be over- 
come in connection with the third require- 
ment of combustion, viz., thorough mixing of 
the air supply with the gases distilled from 
the fuel. This has already been touched 
upon. The requirement is rendered more or 
less difficult of satisfaction by two special 
factors, depending upon the nature of the 
fuel. First, the high percentage of volatile 



406 PREVENTING POWER-PLANT LOSSES 

gases evolved from many waste fuels; and 
secondly, the moisture content. 

The tendency of the volatile portion is to 
flow quickly from the furnace, to become 
chilled below its ignition temperature by con- 
tact with boiler surfaces, and to escape un- 
burned, thus constituting a serious loss of 
heat. One approved method for preventing 
this occurrence is so to construct the furnace 
and setting that predetermined currents will 
be produced which lengthen the travel of the 
gases, check their velocity, cause them to 
consume more time in contact with hot brick 
work in the presence of air, and finally pro- 
duce a thorough mixture of the gases with 
the air for combustion. One of the simplest 
expedients for this purpose is the employ- 
ment of very large and sometimes long com- 
bustion chambers. By merely increasing the 
cross-section of the passage, the velocity of 
the gases is reduced. This method is very 
simply and effectively illustrated by blowing 
through a ^-inch pipe against the palm of 
the hand. The impact of the air is felt, de- 
noting considerable velocity. This " velocity- 
pressure' ' indicates that the current of the 
air is rapid and that a particle or molecule 
passes through the small pipe very quickly. 
Now try the same experiment with a 1-inch 
pipe. The impact against the hand is light, 



WASTE FUELS 407 

and this low velocity-pressure indicates that 
the air is moving slowly and taking a longer 
time to pass through the pipe having the 
larger section or draft passage. The pipe is 
the combustion chamber and the chimney is 
the same capacity in each case, that is to say, 
your own pair of lungs. The only difference 
in equipment is the cross-section of the com- 
bustion chamber. 

By this method, therefore, the gases are 
compelled to remain a longer time in contact 
with hot surfaces, permitting more complete 
diffusion of the fuel gases with the oxygen, 
and thus combustion is promoted and im- 
proved. This feature combined with proper 
baffling to give a mechanical mixing action is 
productive of still better results. But all this 
must be accomplished before the fuel gases 
are allowed to come into intimate contact 
with the boiler cooling (generally called heat- 
ing) surfaces. Other means are also em- 
ployed to bring about this necessary mixing 
of the fuel gases with the air, among which 
may be cited special draft actions and fur- 
naces constructed somewhat on the principle 
of the Argand burner. 

The relation of moisture to the necessity of 
the mixing of the gases is interesting. The 
moisture is evaporated and becomes super- 
heated steam gas. The molecules of this non- 



408 PREVENTING POWER-PLANT LOSSES 

combustible gas tend to form a separating 
medium between the molecules of oxygen and 
those of the combustible gases. Thus the 
element of moisture causes an added oppo- 
sition to combustion and increases the neces- 
sity for, and value of, securing a thorough, 
homogeneous mixture by one means or an- 
other. This point was brought forward by 
Mr. Albert A. Cary, in his discussion before 
the American Society of Mechanical Engi- 
neers of my paper on "Tan Bark as a Boiler 
Fuel." 

With this brief definition of the elements 
of the problem we shall next proceed to a 
description of the means actually employed 
in effective combustion of various waste 
fuels, beginning with sawdust and other 
waste wood products. 

We shall now review the principal waste 
fuels, and show the means employed for their 
effective combustion or utilization. Taking 
them in the order first named, the character- 
istics and treatment of sawdust as fuel will 
be first considered. 

Sawdust and Wood Waste 

This material is of course available princi- 
pally in the lumbering section. Together 
with the sawdust, the saw mills also produce 



WASTE FUELS 409 

waste wood in the form of edgings, end cuts, 
shavings, and various forms of blocks and 
scraps. 

The bulk of this material is so great that in 
many cases not only is the power and heating 
of the mill effected by it, but the whole town 
is furnished with electric lighting, and then 
in order to prevent the accumulation of waste 
wood a large destructor is kept constantly 
in operation, and the heat from the burning 
wood is wasted to the atmosphere. If there 
were a market for electric power within rea- 
sonable distance, this deplorable waste could 
be readily converted into a great economy. 
Even now plans are being considered, and 
at least one plant is in operation for produc- 
ing wood alcohol and other chemicals with 
this material. Inventors have long worked 
on plans which might make possible its use 
as wood pulp in the paper industry. 

Sawdust and wood waste are readily con- 
vertible into gas which may be used for 
power production in gas engines. Informa- 
tion regarding a specific case of this kind 
is given by Mr. Chas. E. Snypp in a paper 
contributed to the Journal of the Association 
of Engineering Societies, reviewed in the Oc- 
tober, 1912, issue of The Engineering Maga- 
zine. 

The burning of sawdust for boiler pur- 



410 PREVENTING POWER-PLANT LOSSES 

poses is best accomplished by means of a 
simply constructed " Dutch- oven ' ' furnace. 
As a rule, only one feed hole in the roof of 
the furnace is used, for sawdust is such an 
excellent fuel that it will produce a hot fire 
even when roughly and carelessly treated. 

Of course with a single feeding hole in the 
top of the Dutch oven, the sawdust forms a 
cone on the grate surface. This is about the 
least effective form in which any fuel may be 
arranged on a grate for burning. The draft 
penetrates the bed of fuel at the points of 
least resistance, that is, at the shallowest 
parts. The air, therefore, enters at an ex- 
cessive rate around the edges of the cone, 
while the greatest portion of the grate is 
effectually air-tight so that this portion of 
the grate surface is "dead." This difficulty 
can be reduced or eliminated by different 
methods which will be later described. But 
as before stated, sawdust will respond with 
fairly good results to even this unskilful 
treatment. 

In a mill where sawdust was plentiful, a 
very effective plant was inspected. A bat- 
tery of six fire-tube boilers were each 
equipped with a Dutch-oven furnace, each 
having a single feed hole in its arch. An over- 
head conveyor brought in a continuous sup- 
ply of sawdust. An iron chute from the con- 



WASTE FUELS 411 

veyor to each furnace led the sawdust to a 
point about two feet directly above the feed 
hole of the furnace. The iron cover of this 
feed hole was left partly open, allowing the 
sawdust to flow into the furnace. By ad- 
justing the sliding doors in the bottom of the 
conveyor, the flow of sawdust onto the grate 
could be made almost automatic. Of course 
a good deal of air entered the furnaces 
through the partly open feed holes in the tops 
of the arches, but the loss on this account 
would not be as great as might appear, for 
the reason that with a heavy pile of sawdust 
in the furnace a sufficient air supply would 
not enter through the grate and therefore 
the supply of air through the feed hole, al- 
though not admitted in a very scientific man- 
ner, was of real advantage. Intense com- 
bustion is actually seen to occur at the inside 
edges of the feed hole where the air meets 
the highly heated gases from the fuel. 

Fig. 36 shows a typical sawdust furnace 
for horizontal tubular boilers. 

Special problems in the combustion of 
wood waste often have to be met. One such 
case in my own experience is perhaps of in- 
terest, owing to the several rather opposing 
conditions that necessitated fulfillment all in 
a single furnace. It was desired to construct 
a burner which would handle with least labor 



412 PREVENTING POWER-PLANT LOSSES 

and greatest efficiency an amount of wood 
material containing sawdust, blocks, end- 
cuts, edgings, shavings, and slabs in vary- 
ing proportions, and also it was further spe- 
cified that the same furnace must be convert- 
ible into a good soft-coal burner at times 
when the wood fuel should not be available. 

Fig. 37 is a cut of the furnace which was 
designed by me to meet these conditions and 
which is doing so in a satisfactory manner. 
Separate storage bins were provided for the 
sawdust and for the bulkier and miscellane- 
ous materials. It was further arranged to 
feed the sawdust alone and separately 
through the top feed hole up to the full ca- 
pacity of the furnace until this supply was 
depleted. Then by sealing the feed hole and 
charging by means of a "pusher" from a 
steel floor, level with the grates, the furnace 
handles, slabs, end-cuts, and the other forms 
of wood at good efficiency. The vertically 
sliding door being capable of quick opening 
and closing prevents excessive entrance of 
air during the feeding operation. When coal 
is fired, this is done through the same sliding 
door and the fuel is either spread or fired by 
the alternate or coking method. 

As the grates are of a proper air spacing 
for fine sawdust, the correct regulating of the 
air supply for the other fuels used is accom- 



WASTE FUELS 



413 



plished by adjusting* the admission of the re- 
quired amount by means of the levers con- 
necting the air valves on the front of the 
furnace. This air becomes pre-heated by the 
walls and combustion arch of the furnace, and 
is admitted to the fire at points surrounding 
the throat, thus producing somewhat the ef- 




Fig. 36. Sawdust Furnace of Dutch-oven Type 

From Steam Power-Plant Engineering, by G. F. Gebhardt. John Wiley 
&Sons 

feet of an Argand burner. The large com- 
bustion space, baffle walls, and explosion 
doors complete the principal features of the 
equipment. 

Although the air requirements and heat 
values of sawdust and coal differ greatly, 
either fuel will develop about the same num- 
ber of heat units per square foot of grate 
surface per hour. It is largely this fact that 



414 PBEVENTING POWER-PLANT LOSSES 




WASTE FUELS 415 

makes possible such an interchange of dif- 
ferent fuels on the same grate and in the 
same furnace. The above furnace was re- 
ported by the owner to be consuming the cal- 
culated amount of wood-waste, and when this 
material is lacking the furnace burns soft 
coal without smoke. The high combustion 
is indicated by 12 per cent C0 2 as average in 
a month's run. 

The heating value of wood depends upon 
the kind of wood in question and also upon 
its state of dryness. 

"Hog feed" is the local term for saw-mill 
refuse which has been fed through a disin- 
tegrator or "hog." The various sizes and 
forms are thus reduced to a practically uni- 
form size of chips, or rather shreds. In this 
condition it is greatly improved for conven- 
ience of handling, lends itself to higher effi- 
ciency in firing, and can be readily mixed and 
fed with sawdust to supplement the latter 
fuel in the same furnace. In the lumbering 
district of Wisconsin, I obtained samples of 
this material in the spring of the year, the 
product being the result of water-soaked 
timber from the mill pond. This material 
contained 52 per cent moisture, and 3.7 tons 
showed available heat value equivalent to 1 
ton of 13,000 B.t.u. coal as tabulated on the 
following page : 



416? PREVENTING . POWER-PLANT LOSSES 

Total heat per dry pound by bomb 

calorimeter test 8,600 B.t.u. 

Moisture, per cent 52 

Total heat in one moist pound 4,128 B.t.u. 

To evaporate moisture to chimney 

temperature of 492 degrees F 650 B.t.u. 

Heat available for boiler per wet pound 

as fired 3,478 B.t.u. 

(13,000 -f- 3,478 = 3.74 tons hog feed = 1 ton coal.) 

Figuring back on the dry wood basis, 100 
pounds of dry hog feed containing 52 per 
cent moisture would produce 208 pounds of 
fuel at 3,478 available B.t.u. = 723,424 B.t.u., 
or one (1) lb. of dry wood produces an avail- 
able heat in the fireroom of 7,234 B.t.u., so 
that tabulating the B.t.u. on four different 
bases we have : — 

1. Heat per pound of dry wood 8,600 B.t.u. 

2. Available heat per pound of wet 

wood as fired 3,478 B.t.u. 

3. Available heat per pound of dry 

wood as fired 7,234 B.t.u. 

4. Total heat in a pound of the wet fuel . 4, 128 B.t.u. 

At this point I beg permission to deviate 
from the specific treatment of wood fuel in 
order to emphasize as clearly as possible a 
matter concerning which there is much con- 
fusion in recorded tests and in reference 
books in reporting the heat values of moist 
fuels. 

The above table exemplifies four correct, 
though different, methods of reporting the 



WASTE FUELS 417 

heating value of such fuels. Unless together 
with the value is also given a clear state- 
ment of how that value is obtained, the infor- 
mation is useless. In fact, it is worse than 
useless, as, four chances to one, it will cause 
a grievous and possibly fatal error in calcu- 
lations intended to produce practical results. 
A glance at the values in this table proves 
that such an error may have a magnitude of 
100 per cent above or below the truth. 

There is indeed a fifth method of obtain- 
ing and reporting a heat value. In the above 
case the fuel was birrned after drying out all 
the moisture. The moisture being separately 
determined, its loss by evaporation and tem- 
perature rise can be readily calculated for 
any set of actual furnace and boiler condi- 
tions. In the table on page 416 the tempera- 
ture of the air entering the furnace was 
taken at 62 degrees and that of the escaping 
waste gases from the boiler at 492 degrees. 

The fifth method is to burn the fuel in the 
bomb calorimeter without removing its con- 
tained moisture. This will give a value per 
pound of "wet fuel as fired" similar to, but 
higher than, value No. 2 in the table ; because 
the moisture is re-condensed in the calori- 
meter and therefore gives up to the record- 
ing water that amount of heat which in the 



418 PREVENTING POWER-PLANT LOSSES 

actual case of burning under a boiler would 
pass ofT up the chimney as an actual loss. 

In consequence of the above, it cannot be 
too strongly urged upon writers and engi- 
neers that they state exactly what is meant 
by the heat values they refer to when dealing 
with moist fuels. Along similar lines and 
with permission again asked, owing to the 
importance of truth in all things, the follow- 
ing point is brought to light. 

If the calorific value of a fuel is deter- 
mined by drying and then burning in a bomb 
calorimeter, the hydrogen contained in the 
substance is burned to steam gas (H 2 0) 
which is condensed in the calorimeter. The 
result in this case gives what is known as the 
"high value," because the condensation of 
the steam produced by the burning of the hy- 
drogen gives back to the calorimeter the la- 
tent heat of the steam thus produced, and this 
heat is measured as part of the heat value 
of the fuel. When, however, this same fuel is 
burned under a boiler from which the prod- 
ucts of combustion escape into the atmos- 
phere at a temperature higher than 212 de- 
grees, the superheated steam formed by the 
burned hydrogen cannot condense and there- 
fore carries with it out of the stack as a loss 
the latent heat of the steam (966 B.t.u. 1 per 

1 See footnote on page 421. 



WASTE FUELS 419 

pound) as well as the heat that was taken 
from the fire to increase the temperature of 
this steam of combustion to the temperature 
of the escaping flue gases. 

The high value of hydrogen as above de- 
scribed is 62,000 B.t.u. per pound. The low 
value is generally taken to mean the high 
value less the latent heat-, without consider- 
ing a final temperature higher than 212 de- 
grees. This "low value" is 62,000 less the 
heat absorbed by the 9 pounds of steam 
(products of combustion of 1 pound of hy- 
drogen). If the temperature of the hydrogen 
before burning is 39 degrees F., then the lost 
heat in the steam will be 9 X ([212 — 39] 
+ 966) = 10,251, which deducted from 62,000 
gives 51,749 B.t.u. as the "low" heating 
value of hydrogen. In some cases only the 
latent heat is deducted, which would make 
this figure 53,306 B.t.u. 

Ordinarily, for commercial purposes, in 
calculating the available heat in a fuel, the 
loss due to burning hydrogen to steam gas is 
disregarded. When specified for some spe- 
cial purpose, however, in connection with a 
boiler test, it is calculated in the same way 
as moisture loss, each pound of hydrogen 
forming 9 pounds of steam or water. 

The determination of the available heat in 
a moist fuel is as follows : 



420 PREVENTING POWER-PLANT LOSSES 

Let weight of fuel as fired = W lb. 

Let percentage of moisture in fuel as fired. . . = M 

Let heat value of dried fuel = H 

Let temperature of fuel as fired = t 

Let temperature of flue gases = T 

Total heat in one pound of the wet fuel is (W — MW) 

H = Total Heat (1). 
Moisture Loss to be deducted from this total heat 

will be: 
Loss, L = M([212 — t] + 966! + 0.48 [T — 212]) 

(2). 
Available heat per pound as fired (1) less (2) = 
(W — MW) H — L. 

Example : Find the available heat per pound as 
fired for steam-making purposes, in a fuel con- 
taining 66 2/3 per cent moisture, and which 
shows when burned in a dry state in a bomb 
calorimeter a heat value of 9,600 B.t.u. per 
dry pound, assuming t = 62 degrees, T = 
S^degrees. 
Total heat in 1 pound of moist fuel = (9,600 — 

[0.66 2/3 X 9,600]) = 3,200 B.t.u. = (1). 
Moisture Loss = 

L = 0.666 ([212 — 62] + 966 + 0.48 [512 — 212]) 
= 840 B.t.u. = (2). 

Available heat per pound as fired, 3,200 — 840 = 
2,360 B.t.u. Answer. 

Now in addition to the accurate bomb-calo- 
rimeter method of discovering the heating 
value of a fuel, upon which I base all my cal- 
culations, another but less accurate method 

1 The work represented by this treatise on waste fuels was largely per- 
formed previous to the adoption of the Marks & Davis Steam Tables. Con- 
sequently the latent heat of steam here appears as 966 (accurately 965.7) 
B.t.u. rather than the modern value of 970.4 B.t.u. For all commercial 
purposes, however, the error introduced by this discrepancy being less 
than Yi of one per cent may be disregarded. 



WASTE FUELS 421 

is employed. An ultimate analysis of the 
material is made by a competent chemist, 
which shows the percentage of each chem- 
ical element. Then as the heat value of each 
of these constituents is known, formulae have 
been devised for calculating with this infor- 
mation what may be the heat value of the 
substance as a whole. The most used for- 
mula for this purpose is that of Dulong, and 
is as follows: — 

B.t.u. per pound = 

14,600 C + 62,000 ( H ~ "^) + 4 > 000 S > 

in which C, H, O and S are respectively the 
percentages of carbon, hydrogen, oxygen 
and sulphur, each divided by 100. 

It is my object to point out in the first place 
that this formula is not correct for fuels con- 
taining any considerable percentage of oxy- 
gen ; and in the second place to show why this 
is true. 

Take for practical example the ultimate 
analysis of tan bark, which is representative 
of w^oody fuels and is composed on the per- 
centage basis as follows: — C — 51.8, H = 
6.04, O = 40.74, Ash = 1.42. Apply Dulong 's 
Formula and we have 
146 + 51.8 + 620 (6.04 — 40.74) = 8,084 B.t.u. 

8 
as the heat value thus derived. 



422 



PREVENTING POWER-PLANT LOSSES 




WASTE FUELS 423 

Over forty actual bomb-calorimeter tests 
have shown, however, that the heat value is 
really 9,500 B.t.u., showing a discrepancy of 
the Dulong formula from the truth of nearly 
15 per cent. So much for the actual fact. 
Now for the reason. Dulong 's formula is 
based upon the erroneous assumption that all 
the oxygen in a compound exists in chemical 
combination with the hydrogen, forming 
H 2 0, thus neutralizing the heat value of as 
many hydrogen atoms as are so combined. 

During the writing of this paper Dr. Henry 
C. Sherman has written a most enlightening 
article on this subject under the title of "The 
Eelation of Chemical Composition to Calori- 
fic Power in Wood, Peat and Similar Sub- 
stances." Dr. Sherman's conclusions are 
based upon fifteen comparisons of calculated 
versus actual bomb-calorimeter values, and 
his summary which follows is the most au- 
thoritative statement on this subject at the 
present time. He states : — 

It may be concluded 

(1) That too much reliance should not be 
placed upon estimates of calorific power from 
ultimate chemical composition in fuels high 
in oxygen. 

(2) That Dulong's formula, or any similar 
formula based on Welter's rule, of calculat- 



424 PREVENTING POWER-PLANT LOSSES 

ing the oxygen with the hydrogen, is likely 
to give results ranch below the trnth. 

(3) That the higher results obtained by 
calculating the oxygen of the sample as com- 
bining with the carbon, according to the sug- 
gestion of Walker, are much more nearly 
correct, and in most cases show a fair ap- 
proximation to the values directly deter- 
mined. 

The foregoing discussion only emphasizes 
the necessity for accurate work and careful 
reasoning in dealing with waste fuels if ac- 
curate testing, high efficiency, and practical 
results are to be obtained. 

To return to the actual handling of wood 
fuels, Fig. 36 shows an ordinary sawdust fur- 
nace of the Dutch-oven type such as is com- 
monly found in the lumbering and saw-mill 
districts. It has the single top-feed hole and 
provides the characteristic cone-shaped bed 
of fuel on the grate. The inefficiency of draft 
distribution around the edges of this cone 
and the inflow of unmixed air through the 
feed hole have been discussed. 

Fig. 38 shows a sawdust burner designed 
to overcome both of these difficulties and also 
to provide automatic feeding of the fuel at 
precisely the rate at which combustion takes 
place. The V-shaped grate receives two flat 
streams of sawdust from the lower open ends 



WASTE FUELS 425 

of cast-iron or firebrick chutes of rectangu- 
lar section which are kept filled with the 
fuel. As the fire consumes the sawdust, more 
is automatically supplied by gravity and a 
bed of fuel of unvarying thickness and effi- 
ciency is maintained. The thickness of the 
fuel can be changed at will to suit the draft 
by raising or lowering the feed chutes. Even 
draft distribution is obtained by the flat in- 
stead of the cone-shaped beds of sawdust, 
which greatly increases the rate of combus- 
tion and permits a smaller furnace being 
used. The grates are of the special type used 
in my stoker tan and chip furnace, and give 
a blow-pipe or concentrated draft action 
later described in connection with Fig. 42. 

When operating on wet sawdust of 8,600 
B.t.u. per dry pound, and containing 52 per 
cent moisture, the expected evaporation 
should be in the neighborhood of 2.5 pounds 
of water from and at 212 degrees per pound 
of sawdust, weighed as fired, with a combined 
thermal efficiency of boiler and furnace of 70 
per cent of the available heat in a pound of 
the fuel as fired. 

Tan Baek 

It is believed that tan contains a larger 
percentage of moisture than any of the other 



426 PREVENTING POWER-PLANT LOSSES 

moist fuels. It is true, therefore, that its 
correct treatment as a fuel has valuable bear- 
ing on the correct handling of other moist 
fuels for high combustion efficiency. 

The practical treatment of tan bark for 
high efficiency may be concisely outlined, first 
by a partial quotation from the summary of 
my paper on this subject read before the 
American Society of Mechanical Engineers 
at the annual meeting of 1909; and further 
by supplementary information with refer- 
ence to illustrations of furnaces given here- 
with. The paper was the result of some forty 
tests on this fuel under actual conditions in 
various furnaces and settings. 

Moisture: — In condition for firing, wet 
spent hemlock tan usually contains close to 
65 per cent of moisture. 

Available B.t.u. : — Bomb calorimeter tests 
on many samples of spent hemlock tan give 
an average value of about 9,500 B.t.u. per 
pound, samples being dried before burning. 
The average available heat per pound as 
fired, after subtracting moisture loss, is 
about 2,665 B.t.u. 

Effect of Leaching on B.t.u. : — The heat 
value of spent hemlock tan is not affected by 
the degree of leaching, except inasmuch as 
the actual weight is affected. 

Chemical Composition: — This has been 



WASTE FUELS 427 

quoted in the previous discussion on Du- 
long's formula. 

Improved Efficiency: — A considerable im- 
provement in efficiency was produced by a 
specially designed furnace providing auto- 
matic feeding, large combustion space over 
the fuel and special draft admission. 

Presses : — The use of presses for reducing 
the moisture before firing may constitute 
good economy if the amount of tan compared 
to the amount of coal is considerable, and 
providing the grate surface is properly re- 
duced to meet the demands of more rapid 
combustion. The grate surface is sometimes 
reduced one-third. The gain in available 
heat is about 1% per cent for each per cent 
drop in moisture, and this drop rarely ex- 
ceeds 7 per cent, i. e., a reduction of moisture 
from say 65 to 58 per cent. 

Addition of Coal: — As a result of special 
comparative tests, the addition of about one 
pound of coal to six of pressed tan increased 
the combined furnace and boiler efficiency 
from 59.4 per cent to 63.4 per cent. The av- 
erage C0 2 in the flue gases was raised from 
•10.9 to 13.8 per cent. The output of the boiler 
was increased from 92 per cent to 135.5 per 
cent of its rating. A further increase of 
efficiency would have resulted in a furnace 



428 PREVENTING POWER-PLANT LOSSES 

especially designed for burning a mixture of 
coal and tan. 

Ample Combustion Space: — One of the 
most important factors in designing fur- 
naces for tan-burning is that of ample com- 
bustion space. Low-arched furnaces are con- 
ducive to bad combustion. 

Eefractory Arch: — A refractory arch or 
similar combustion arrangement is essential. 
Tan in its usual condition cannot be burned 
in a common coal-burning setting without an 
arch separating the fire from the cooling 
surface of the boiler shell or tubes. 

Furnace Temperature : — Excellent com- 
bustion of tan has given 1,500 degrees in the 
throat of the furnace. 

Flue-Gas Analyses : — Basing comparison 
on flue-gas analyses, tan burns with a higher 
combustion than coal under equally favorable 
conditions. The large amount of moisture in 
tan produces comparatively low furnace tem- 
perature, even with good chemical combus- 
tion, and acts against an equally high com- 
bined efficiency of furnace and boiler. 

The furnaces found throughout the coun- 
try differed considerably in design and in re- 
sults. Owing to the previous lack of testing 
no rationally fixed formulae existed, and con- 
sequently the furnaces were designed prin- 



WASTE FUELS 



429 



cipally on somebody's idea of what might 
give improved results. 

All the furnaces had a Dutch-oven con- 
struction with different numbers of feed holes 
in the roof of the arch. Some were deep. 
Some were shallow. Occasionally a double- 
arched furnace was found. Combustion 
chambers were sometimes large, sometimes 
small ; and systems of firing were found that 
suited the convenience and disposition of the 




Fig. 39. Early Type of Furnace for Burning Tan 



firemen rather than the economy of the fuel 
and the design of the furnace. 

Generally speaking the poorest results 
were found in low-arched furnaces and with 
heavy firing at long intervals. Much diffi- 
culty resulted from the cone-shaped beds of 
fuel heavily packed upon the grates with the 
draft ripping up the light edges into blow 
holes and cooling the furnace. 

Ordinarily found types of tan furnaces are 
shown in Figs. 39 and 40. The first repre- 
sents one of the earlier types, very long with 



430 PREVENTING POWER-PLANT LOSSES 

a single row of feed holes. This was known 
as the Hoyt furnace, and where there was a 
large excess of tan to be destroyed this fur- 
nace answered that purpose. 

Fig. 40 is a more modern type with a dou- 
ble row of feed holes for more even distribu- 
tion of fuel on the grate and shows a second- 
ary air supply in the bridge-wall. 

Fig. 42 shows my special design of auto- 
matic-stoker furnace which was successfully 




Fig. 40. Later Type "of Furnace for Burning Tan 

used in modern plants, and under test showed 
a combined efficiency of boiler and furnace 
of 71.1 per cent based on the available heat 
in the tan. 

The essential features combining to secure 
these improved results, as. will be noted from 
the cut, are: (1) large combustion space 
over the fuel bed; (2) automatic and con- 
tinuous feeding of the fuel at the exact rate 
of combustion; (3) drying before receiving 
air supply by passing over dead plates at 
the upper edges of the grates ; (4) discharge 
of ash by shaking grate at bottom of furnace ; 



WASTE FUELS 



431 



and (5) special draft action as shown in Fig. 
41. Owing to the horizontal air-spacing in the 
oppositely inclined grate surfaces, the draft 
currents arrive at a focus of combustion in 
the central zone of the furnace in a manner 
similar to the two flames of an acetylene gas 




Fig. 41. 



Showing Draft Action of Furnace Illustrated 
in Fig. 42 



burner. By means of temperature differ- 
ences and mechanical impulse, the flames or 
currents then react upon the dead plates, 
thus drying the fuel thereon ; while the vola- 
tile gases that are distilled off are drawn 
downward into the focus of combustion 
where they meet the effective combination of 
high temperature and air supply and are 
thus consumed at full efficiency. 



432 



PREVENTING POWER-PLANT LOSSES 




< 

En 



Q 






P 

fe 



3 



WASTE FUELS 433 



Mixture Burning 



Owing to shortage of tan bark and to in- 
creased nse of steam in the modern tannery, 
it has been necessary to develop a mixture- 
burning furnace. Fig. 43 shows two of the 
author's recent installations designed to 
meet special requirements of this kind. Fea- 
tures to be noted are: (1) large combustion 
space; (2) a strong set of shaking grates as 
the clinker is bad with this kind of mixture ; 
(3) heated auxiliary air supply; (4) special 
bridge wall for baffling; (5) small grate sur- 
face; and (6) provision for top feed through 
four holes and bottom front stoking by hand 
if desired. These furnaces operate with a 
heavy mixture of soft coal without smoke. 

Chestnut-Extract Chips 

Chestnut-extract chips are a more difficult 
fuel than tan, as they contain less heat 
and as much moisture. This fuel has been 
touched upon in another part of this paper 
and is one of those which have recently been, 
changed from a semi-combustible to an auto- 
combustible. The author's tan furnace 
shown in Fig. 42 was successful in solving 
this particular problem. 

This fuel was ordinarily handled in com- 



434 



PREVENTING POWER-PLANT LOSSES 




WASTE FUELS 435 

mon tan furnaces, but would not burn with- 
out the application of coal. This extra fuel, 
of which large quantities were consumed, was 
in some cases mixed or " dumped" into the 
same furnace with the chips. In one of the 
large plants, the coal supply was stopped 
and when conditions became normal an evap- 
orative test showed about 25 per cent com- 
bined efficiency of boiler and furnace. Even 
with the coal, continuous and dense smoke 
was produced. The furnace had many feed 
holes but a very low arch. 

In other cases the coal was burned on a 
separate grate in the rear of the chip fur- 
nace, and the heat thus developed ignited the 
chips and maintained a slow inefficient com- 
bustion. 

In one plant eight of the automatic- stoker 
tan furnaces, before referred to, burned these 
chips without any coal, with a combustion effi- 
ciency which produced continuous readings 
of 12 to 14 per cent C0 2 , developed no smoke, 
gave over full rating of boiler horse power, 
and showed an operating saving of many 
thousands of dollars a year over a duplicate 
plant using the old-time furnaces with aux- 
iliary coal grates. These observations, from 
the commercial standpoint, emphasize the 
important relation of scientific furnace-de- 
sign to industrial efficiency. 



436 PREVENTING POWER-PLANT LOSSES 

Licorice Chips 

Extracted or spent licorice-root chips are 
similar in general composition to chestnut 
chips, and I inspected a furnace that was 
very successful in burning the former fuel at 
high efficiency. The construction was along 
the general lines of an Argand burner. The 
fuel was fed into a Dutch oven in a heavy 
bed wherein sufficient temperature was main- 
tained to gasify the chips. The resultant 
gases flowed through the furnace throat into a 
cylindrical combustion chamber, in whose 
centre was a hollow checker-work of brick by 
means of which a preheated air supply en- 
tered and mixed with the fuel gases. The 
brick checker-work of the Argand burner to- 
gether with the combustion chamber walls 
maintained a high temperature, thus promot- 
ing the ignition and combustion of the gases 
which were well mixed with the preheated air 
supply by means of the Argand feature. 

Bagasse 

Bagasse is the by-product fuel resulting 
from the manufacture of cane sugar. The 
juice from the ripe cane is extracted by 
crushing in powerful mills. The remaining 
fibrous material, known as bagasse, is con- 
veyed to the boiler house where it is fired in 



WASTE FUELS 437 

special furnaces and is made to produce all, 
or part of, the steam required to operate the 
plant. The fuel is in the form of strips from 
3 to 8 inches long, but very much longer 
pieces may come through the mills. 

In regard to the heat value of bagasse, Dr. 
Sherman made determinations on a Cuban 
sample imported by the author in an air-tight 
can (to retain the moisture). This sample 
showed: — B.t.u. per dry pound, 8,324; mois- 
ture, 57.9 per cent. 

If this were burned under a boiler giving 
a flue temperature of 594 degrees Fahren- 
heit, the heat per pound of fuel, weighed as 
fired, available for steam purposes would be 
([100 per cent — 57.9 per cent] 8,324 — 57.9 
per cent ([212—62] + 970 + 0.48 [594— 
212] ) = 2,750 B.t.u. 

Mr. E. W. Kerr, who has made a study of 
bagasse burning in different styles of fur- 
naces, is quoted from Bulletin 117 of the 
Louisiana Agricultural Experiment Station 
as follows: 

"An equivalent evaporation of 2% pounds 
of steam from and at 212 degrees w T as ob- 
tained from 1 pound of wet bagasse of a net 
calorific value of 3,256 B.t.u. This net value 
is that calculated from the analysis by Du- 
long's x formula, minus the heat required to 

1 See author's discussion of Dulong's formula, pages 421-424. 



438 PREVENTING POWER-PLANT LOSSES 

evaporate the moisture and to heat the vapor 
to the temperature of the escaping flue gases, 
594 degrees Fahrenheit. The approximate 
composition of bagasse of 75 per cent ex- 
traction is given as 51 per cent free moisture, 
and 28 per cent of water combined with 21 
per cent of carbon in the fibre and sugar.' ' 
"For the best results bagasse should be 
burned at a high rate of combustion at least 
100 pounds per square foot of grate per 
hour. ' ' 

For obtaining quick combustion mechan- 
ical draft is used in many plants, the draft 
being admitted to the fuel from under the 
grates and also through tuyeres in the fur- 
nace walls. This is illustrated in Fig. 44, 
kindly contributed by a test record by Dr. 
D. S. Jacobus, Advisory Engineer of the B. 
& W. Boiler Company. This furnace is 
shown in connection with a Stirling boiler 
installation. Other features to be noted as 
conducive to efficiency are: (1) The very 
large combustion chambers that are provided 
for retaining the gases at a high tempera- 
ture to afford sufficient time for combustion 
before cooling by contact with the boiler 
tubes. Combustion chambers for bagasse 
are made larger than for any of the waste 
fuels previously mentioned. (2) The well- 
designed baffle walls for mixing the gases 



WASTE FUELS 439 

with the oxygen and for retaining a high tem- 
perature. (3) The automatic feed hoppers 
which by means of engine or motor-driven 
rolls stoke the bagasse at a uniform rate 
through the furnace roof. From there it falls 
upon the grate in mounds. There are two 



Fig. 44. Stirling Boiler Set with Furnace for Burning 
Green Bagasse 

of these in the illustration, owing to the large 
size of the boiler. Ordinarily only one is pro- 
vided. 

Test results show practical agreement with 
those quoted from Kerr. In neither case, 
however, was the heat value of the fuel ob- 
tained with a bomb calorimeter so that no 



440 PREVENTING POWER-PLANT LOSSES 

accurate deductions can be made as to the 
absolute efficiency of the furnace and boiler. 
Again, with this fuel also, the same difficulty 
in operation arises which has been mentioned 
in connection with other waste fuels — that is, 
the trouble which results from having the 
fuel in the form of cones on the grate, 
which prevents uniform distribution of the 
draft through the fuel. Furthermore, the 
' ' feast and famine ' ' condition is a very hard 
one to overcome in the average sugar-mill 
boiler room. Owing to a little inattention by 
the firemen the furnaces are allowed to be- 
come so full of bagasse that the fires are 
choked and cooled. This is the feast condi- 
tion. The famine occurs when the bagasse 
is not fed fast enough and the grates blow 
bare in spots around the edges of the heap of 
fuel and the furnaces are again chilled by the 
excessive amount of cold air thus admitted. 
The principal values given in the test rec- 
ord are as follows : 

RECORD OF TEST OF BAGASSE BURNING 
Boiler and setting illustrated in Fig. 44 

Duration of test, hours 6 

Heating surface, square feet 5,750 

Grate area, square feet 160 

Kind of fuel Bagasse 

Per cent moisture 42 . 21 

Equivalent water actually evaporated from 

and at 212 degrees, pounds 165,682 



WASTE FUELS 441 

Economic Results 

Water evaporated per pound of bagasse 

from and at 212 degrees 2 . 46 

Water evaporated per pound of dry bagasse 

from and at 212 degrees 4 . 41 

Water evaporated per pound of combus- 
tible from and at 212 degrees 4. 50 

Rate of Combustion 

Fuel actually burned per square foot of 

grate per hour, pounds 70 . 2 

Dry fuel actually burned per square foot of 
grate per hour, pounds 39 . 1 

Horse Power 

Builders' rating in horse power 500 

Per cent developed above rating 60 

Fig-. 45 illustrates a bagasse furnace of the 
author's that has been designed to reduce 
these common troubles as far as possible. 
Two flat fuel beds are provided on the V- 
shaped grates which eliminate the first diffi- 
culty, the feed hoppers being at the sides in- 
stead of the centre of the grate. The grate 
bars are of the type shown in Fig. 46; they 
produce the opposed blow-pipe effect of draft 
and flame, and the fuel falls from the side 
hoppers upon the dead plate for drying and 
gradually feeds over the grate surfaces as 
combustion takes place. The "feast" con- 
dition is more difficult to obtain with this ar- 
rangement as it would be impossible to have 



442 



PREVENTING POWER-PLANT LOSSES 







1 i 


1 








F 1 




i 

T 






WASTE FUELS 443 

a heap of bagasse rising to the top of the 
furnace arch, and with the fastest rate of 
feeding possible there would always be a 
V-shaped combustion space directly over the 
bed of fuel. The "famine'' condition may 
occur with any possible design if the fuel 
supply is reduced below the rate of combus- 
tion, and some attention is essential to even 
fair results. 




Fig. 46. Grate Bars for Myers's Bagasse Furnace 

Bagasse forms a heavy and troublesome 
clinker, and a heavy shaking grate is pro- 
vided at the bottom of the V-grate to reduce 
the labor and heat losses of hand clinkering. 
Improvement is much needed in furnace de- 
sign and furnace control in many bagasse- 
burning plants. These two factors will often 
make the difference of running the boiler 
plant on very little or no purchased fuel, 
and on the other hand of spending large 
sums annually for the buying of coal and oil. 

Culm 

Anthracite culm is, practically speaking, 
the^dust from this coal. The coal from the 



444 PREVENTING POWER-PLANT LOSSES 

mines is screened and graded according to 
size, each size bearing its own name. The 
smallest marketable size is No. 3 buckwheat, 
sometimes called barley. This grade will 
pass through 3/16-inch and will be retained 
on 3/32-inch round meshes. Below this there 
is no grading, and the fine " waste fuel" that 
falls through the last screen is known as 
culm. (See Fig. 21.) 

This material has constituted until recent 
years a large waste of fuel. Its very fine- 
ness makes it difficult to burn as, in the first 
place, it opposes the penetration of draft on 
the grate; and in the second place, under 
other conditions is caught up by the draft 
and is blown off up the flue as a dead waste. 
To emphasize the difficulty surrounding the 
problem of its efficient combustion, it may be 
stated that even No. 3 buckwheat demands 
especially-designed furnaces and scientific 
treatment in order to obtain economic com- 
bustion. 

Briquettes 

Considerable experimenting has been done 
in the way of briquetting culm for the pur- 
pose of increasing its efficiency. At the pres- 
ent prices of other coals this method is doubt- 
ful of success, although a very marked im- 



WASTE FUELS 445 

provement in combustion is possible. But 
the manufacture of briquettes is expensive, 
requiring special machinery for pressing as 
well as a binder for maintaining the strength 
and form of the moulds. The binders that 
have been tried are flour, water-gas pitch, and 
residue from heavy oils. The total cost of 
making briquettes has been from $1.00 to 
$1.50 per ton, which together with the freight 
and the cost at the mines makes the delivered 
price of the fuel prohibitive when used in 
this way for boiler purposes, at least in most 
cases. 

Some experimenting has also been done in 
the way of pulverizing anthracite culm to a 
very fine powder, about 1/125- to 1/200-inch 
mesh, and then burning it in a brick-lined 
furnace into which it is blown by a current 
of air. This has not yet been developed to 
the stage of a commercial proposition. The 
method has been successfully used, however, 
for bituminous coal dust, which ignites more 
readily owing to its higher content of volatile 
matter. The fuel burns like a gas in the fur- 
nace and has thus been used in connection 
with cement kilns to considerable extent. A 
high temperature is obtained and the com- 
bustion admits of easy regulation and small 
labor and is smokeless. 

One of the most modern and successful 



446 PREVENTING POWER-PLANT LOSSES 




WASTE FUELS 447 

powdered-coal burners is shown opposite in 
Fig. 47. This device is the invention of Wil- 
liam B. Dunn, and is used most successfully 
in connection with kilns in the Portland ce- 
ment industry. It will be noted that the coal 
in the form of dust is fed by the screw con- 
veyor to a perforated cylinder, from which 
it is dropped into an annular space surround- 
ing the nozzle "C," which furnishes air at 
this point under high velocity, thus acting 
like an injector on the fine coal powder. An 
auxiliary air pipe is provided which may be 
supplied with heated air from the clinker 
pit, means being provided for the accurate 
regulation and proportioning of air and fuel. 

Greater success, and in fact very decided 
success, has been gained by improvement in 
design of furnaces for burning culm in its 
untreated natural condition. 

The successful type of furnace is one which 
combines well-proportioned and controlled 
mechanical-draft apparatus with properly 
designed fire-brick arches. The fuel has a 
low volatile content so that very large com- 
bustion chambers are unnecessary, although 
chambers are sometimes advisable for the 
purpose of arresting and depositing dust 
that may be carried over from the fire. 

The air is supplied under pressure beneath 
the grate in a closed ashpit at sufficient in- 



448 PREVENTING POWER-PLANT LOSSES 

tensity to penetrate the bed of culm Tinder 
all conditions of the fire. The under-grate 
pressure may be regulated by draft-admis- 
sion doors to the ashpit. The amount, or 
volume, of air supplied to the culm is of high- 
est importance and this volumetric regula- 
tion is effected principally at the damper in 
the uptake of the boiler. This damper is fre- 
quently controlled by an automatic regula- 
tor which partly closes and opens as the 
steam pressure in the boiler rises and lowers. 
But the damper must first be set by hand to 
give the correct throttling effect between the 
determined extremes of operation of the 
boiler. Furthermore, care must be taken to 
increase the rate of firing as the damper 
opens wider, and to reduce the feeding of fuel 
as the draft decreases. If these precautions 
are not followed, the damper regulator may 
operate to reduce the air flow for a heavy 
fire and to increase the air for a light fire, 
thus destroying instead of improving the 
economy. In other words, the usual form of 
automatic damper-regulator works as a func- 
tion of the varying steam pressure, which 
latter depends not alone on the rate of com- 
bustion but as well upon the rate of steam 
flow from the boiler. This is a point rarely 
mentioned, if recognized, by promoters of 
this class of damper-regulators. 



WASTE FUELS 449 

Control of the under-grate draft is fre- 
quently effected by means of the same class 
of damper regulator as above referred to. 
In this case, however, a balanced valve is in- 
serted in the steam line to the fan engine, or 
in the supply pipe of a steam blast which is 
often used to create air supply under pres- 
sure. 

This balanced valve is connected to the 
damper regulator and by this means the sup- 
ply of steam to the fan or blower is regu- 
lated in accordance with variations of the 
steam pressure at the boiler. The same pre- 
cautions are necessary with this contrivance 
as have been indicated in connection with the 
opening and closing of the damper when the 
control of the draft is effected in that way. 
That is to say, when the draft increases, an 
increase in the rate of firing must also be 
made, and vice versa, for the purpose of 
maintaining the air and fuel supply in proper 
relation to each other. 

A well constructed set of dumping grates 
for disposing of the clinker, and also the ad- 
mission of steam under the grates for soften- 
ing this clinker, are valuable adjuncts to a 
culm-burning furnace. A careful study of 
conditions is essential to determine the eco- 
nomic ratio of grate surface to the heating 
surface of the boiler. 



450 



PREVENTING POWER-PLANT LOSSES 




WASTE FUELS 451 

The notable advance in the utilization of 
anthracite culm on a large scale is indicated 
by the plant of the Harwood Electric Com- 
pany, Harwood, Pa., where twenty-two 950- 
horse-power boilers are installed to operate 
on this fuel which costs them about five cents 
per ton, delivered. By burning the culm di- 
rectly at the mines, the cost of freight is 
eliminated and cheap electric current is gen- 
erated for high-tension distribution through 
the surrounding territory. 

Another similar plant is planned for Mauch 
Chunk, Pa. The entire supply of culm is to 
be contracted for at the rate of a few cents 
per ton. The ash and clinker are to be sold 
back to the mines for filling-in purposes, 
which still further reduces the net cost of 
fuel. /The culm is to be burned in special 
furnaces designed along the lines described, 
and briquetting will not be necessary. 

Thus a valuable by-product which was for- 
merly considered a mere waste and great det- 
riment and was piled up into the enormous 
culm heaps familiar to the anthracite region, 
has at last by virtue of scientific furnace de- 
sign come into its own to fill an important 
place in the great economy of power genera- 
tion. 

Fig. 48 illustrates a culm-burning furnace 
and boiler setting, using McClave-Brooks 



452 



PREVENTING POWER-PLANT LOSSES 



dumping grates and fire-brick arches ; the lat- 
ter for the double purpose of maintaining ig- 
nition temperature over the fire and for 
checking the flight of dust particles that may 
be caught up by the draft. 

The following data in Test B are taken 
from a complete test on a McClave equip- 
ment, while Test A shows the comparatively 
poor results on a furnace without an arch 
over the fire. 







TestB 


Location of Plant, Reading, Pa. 


Test A 


Projected 


Kind of Boiler, H.T. 


Regular 


Furnace 


Fuel, River Coal Refuse 


Setting 


McClave 

Design 


Ratio grate to heating surface 


1 to 50 


1 to 40 


Water-heating surface, sq. ft. 


1,949 


1,949 


Per cent moisture in coal . . . 


9.06 


10.63 


Dry fuel burned per sq. ft. 






grate surface per hour 


16 


15 


Horse power developed 


158.7 


202.76 


Equivalent evaporation from 






and at 212 degrees per lb. 






coal as fired 


7.96 


8.6 


Equivalent evaporation from 






and at 212 degrees per lb. 






dry coal 


8.75 


9.633 


Percentage of ash in dry coal 






Percentage of volatile in dry 






coal 






Calorific value of the dry 




coal per lb. ; B.t.u w 


12,724 


12,178 


Efficiency of boiler, including 






furnace (based on dry 






coal), per cent 


66.4 


76.39 



WASTE FUELS 453 

The culm used in these tests makes a strik- 
ing" example of the reclaiming of waste fuel, 
for the material used is known as " river 
coal refuse." This consists of "tailings" 
which compose the waste from the screening 
and washing, and which are carried into the 
river. These tailings are made up chiefly 
of culm under 3/32-inch mesh with some 
small proportion of coarser particles. This 
coal dust settles where it may on the river 
bottom and is dredged up for use under boil- 
ers equipped with special furnaces for its 
combustion, a true example of reclamation. 

An inspection of Fig. 48 will show the spe- 
cial method of preheating air over the fur- 
nace arch and of introducing this air under 
pressure in such a manner as to cause a 
forced intermingling or mixing action in the 
furnace with the fuel gases. Another heated- 
air admission to still further increase this 
effect and to cause a whirring or baffling 
action is shown at the bridge wall of the fur- 
nace. The blast is caused by steam blowers 
which also reduce and soften the formation 
of clinker. Dumping grates of special con- 
struction facilitate the cleaning of fires. 

A Parson system culm furnace is shown 
in Fig. 49. This also is of the Dutch-oven 
type and the draft is furnished by steam- 
blast apparatus. An automatic draft regula- 



454 



PREVENTING POWER-PLANT LOSSES 



tor of the general type previously referred 
to is shown as a part of this equipment, and 
a secondary air supply is provided over the 




Fig. 49. Culm-burning Furnace on the Parson System 



fire. The Parson Co. kindly furnished the 
following test made under forced conditions, 
which illustrates the combustion of a fresh- 
mined culm consisting of 13.55 per cent rice, 
44.8 per cent barley and 41.65 £er cent 



WASTE FUELS 455 

"dirt," the last constituent indicating, no 
doubt, fine dust. 

Test on Parson System 

Fuel used Fresh- 
mined culm 
Ratio of grate surface to heating surface . 1 to 37 . 3 

Water-heating surface, sq. ft 3,030 

Per cent moisture in coal 3 

Dry coal burned per sq. ft. grate surface 

per hour 22.26 

Horse power developed 447 . 3 

Equivalent evaporation from and at 212 

degrees per pound of coal as fired ..... 8 . 35 

Equivalent evaporation from and at 212 

degrees per pound of dry coal 8.61 

Coke Braize 

When gas is made by destructive distilla- 
tion of soft coal, which is the older method 
employed for city gas production, there is 
left as one of the important by-products a 
finely divided coke. The volatile gases have 
been driven off, so that the coke that remains 
is principally carbon which is naturally high 
in ash. The particles are about the size of 
No. 2 or No. 3 buckwheat coal, and it can be 
successfully used as a boiler fuel with proper 
furnace equipment. It is capable of compet- 
ing with the fine sizes of low-priced anthra- 
cite coal. 



456 PREVENTING POWER-PLANT LOSSES 

Coke braize is best burned with an under- 
grate draft pressure of considerable inten- 
sity. A draft pressure of 1-inch water gauge 
was used in a test made by the author. This 
draft was supplied by a steel-plate fan de- 
livering into the closed ashpits of two water- 
tube boilers. Some of the results and data 
are as follows: 

Test of Burning Coke Braize 

Cost of coke braize per long ton delivered .... $2 . 30 

Percentage of ash 21 

Evaporation per lb. of coke braize from and at 

212 degrees, lb 6.25 

Evaporation per lb. of combustible from and 

at 212 degrees, lb. 7.53 

Cost to evaporate 1,000 pounds of water into 

steam from and at 212 degrees $0 . 164 

CO2 — average in flue gases, per cent 10 . 25 

The principal characteristics developed in 
burning this fuel are : 

1. A very hot fire with long flame. 

2. Formation of a large amount of very 
hard and troublesome clinker. 

It was found by experiment that by mak- 
ing the coke braize very wet before firing re- 
sults were much improved. The moisture 
softened and reduced the clinker materially. 
Better results could undoubtedly have been 
obtained with further practice. 



waste fuels 457 

City Kefuse 

City refuse belongs to the class of fuels 
which, by application of the scientific prin- 
ciples of combustion, have been promoted 
from the state of semi-combustible into that 
of auto-combustible fuel. 

While this heterogeneous material can be 
disposed of by dumping at sea or on waste 
land — sometimes in an inexpensive manner 
— the consensus of opinion is strongly in 
favor of its disposition by combustion. The 
strength of this opinion is largely due to com- 
paratively recent improvements made in the 
design and efficiency of destructors or refuse 
burners. Furthermore, when combustion is 
complete, burning is by far the most sanitary 
method of disposing of this and other offen- 
sive materials. 

It is a notable achievement of engineer- 
ing study and skill that has made possible 
not only the smokeless and complete combus- 
tion of city refuse, but also the production of 
useful heat and power from this former 
waste. 

Some of the collected matter, principally 
the house garbage, contains so much mois- 
ture in comparison with its low heating value 
that to burn it alone would be impossible. 
But by mixing this with all the other matter, 



458 



PREVENTING POWER-PLANT LOSSES 



the calorific value of the mass is made suffi- 
ciently high not only to evaporate its con- 
tained moisture but to produce effective 
evaporation in a boiler as well. Even when 
this is done, however, it is necessary to de- 
pend for efficiency upon scientific design and 
careful operation of the furnace. 

To gain an idea of the composition of city 
refuse, a quotation is herewith given from 
the acceptance tests made on a Heenan- 
Froude destructor in operation on Staten 
Island, N. Y., at West Brighton. This is an 
English design of burner and the tests were 
conducted for the city by their engineer, Mr. 
Fetherston, to whom the author owes his ac- 
knowledgments. 

Test of Garbage Burning, Heenan-Froude 
Destructor 





Test No. I 1 


Test No. 2* 


Garbage 3 


46.6 

21.71 

7.7 

0.6} 

8.5 
14.9 


11.8 


Fine ash 




Coal and cinders 


79.5 


Clinker 

Glass and metals 


3.4 


Rubbish 


5.3 







*Sept. Mixture. Prepared artificially. 
2 Feb. Mixture. Prepared artificially. 
3 Garbage consists of animal and vegetable matter. 



WASTE FUELS 



459 



Test No. 1 



Test No. , 



Date, 1908 

Duration, hours 

Material (see above notes) . . 
Evaporation per lb. of refuse 

burned, gross actual lb. . . . 
Net useful steam for power 

purposes from and at 212 

degrees, lb 

C0 2 average per cent 

Temperature of chimney 

gases 



May 6 

8 
Sept. Mix. 

1.17 



1.31 

12.2 



393 



May 13 

8 

Feb. Mix. 

1.10 



1.24 
12.5 

364 



The capacity of this burner is 60 tons per 
day and is the first of this design installed in 




Fig. 50. 



General Design of the Heenan-Frotjde Refuse 
Destructor 



the United States. A cut showing the gen- 
eral design is given in Fig. 50. Fig. 52 
(page 461) shows an exterior view of the 
West Brighton Plant. 

Some of the features of especial note are 



460 PREVENTING POWER-PLANT LOSSES 

the very large combustion chambers, the pre- 
heated air supply delivered under pressure 
below the grates, and the division of the 
space below the grate so that the draft can 
be shut off for any one section while clink- 
ering. 

An additional feature has been successful- 
ly attained by passing the air supply for the 
furnace through the white hot clinker, which 
performs the double function of cooling the 
clinker for handling and of reclaiming much 
of its heat for the improvement of the fur- 
nace efficiency. Mr. Fetherston has done val- 
uable work in this connection. The exhaus- 
tive tests made by him for the City are re- 
corded in Vol. LX of the American Society 
of Mechanical Engineers. 

Colonel Wm. F. Morse has made valuable 
contribution to this field of municipal waste 
disposal through his deep study and impor- 
tant book on the ' i Collection and Disposal of 
Municipal Waste,' ' through his own design 
of destructors, and through his experience in 
the handling of such problems. 

Colonel Morse acts also in consulting ca- 
pacity in connection with the construction in 
this country of the Sterling destructor. This 
is also an English furnace and it is largely 
used in European and other countries. Fig. 
51 gives an idea of the design of this burner. 



Temporary End 
Extension, 

this Side, 




Pressure Air Main Th < *»»<««H«» * <■»«<»« ' 

Fig. 51. Plan and Elevation of the Steeling Refuse Destructor 



WASTE FUELS 461 

One feature of especial importance for this 
fuel, used by various destructor companies, 
is shown clearly on this cut, i. e., the drying 
hearths or dead plates. In charging, the wet 
fuel is placed upon these where it is made 




Fig. 52. The Heenan-Froude Refuse Destructor at 
West New Brighton 



sufficiently dry for burning before being 
raked over onto the real grate surface. 

Evaporative results vary with the compo- 
sition of the refuse, but l 1 /^ pounds of steam 
from and at 212 degrees per pound of refuse 
appears to be a usual figure for guarantees 



462 PREVENTING POWER-PLANT LOSSES 

when " average' ' refuse is supplied. Consid- 
erably higher results have been obtained in 
the official tests recorded. An English Ster- 
ling plant officially reports, as an average 
for one year, an evaporation per pound of 
refuse destroyed of 1.4 pounds of water into 
steam. 

The clinker that results from the burning 
of city refuse is crushed, combined with Port- 
land cement, and formed into concrete blocks 
useful for building purposes. These are sold 
and thus reduce the cost or increase the profit 
of operation of the plant. 

In further relation to composition of city 
refuse, Mr. George Watson in a paper before 
the Institution of Mechanical Engineers 
states that " it is a fairly safe generalization 
to say that in England it consists of one-third 
by weight of water, one-third combustible 
matter, and one-third incombustible. ' ' This 
last is the portion withdrawn in the form of 
clinker to be crushed and formed into blocks 
for building or other purposes. 

In the early days of refuse destructors 
they were operated entirely on natural chim- 
ney draft. A partial vacuum was thus al- 
ways present in the furnace. Since the clink- 
ering and charging operations required that 
the furnace doors should remain open a con- 
siderable time, very great volumes of cold 



WASTE FUELS 463 

air would enter the furnace by virtue of the 
higher pressure of the atmosphere outside. 

To Mr. William Horsfall is credited the 
correction of this cause of inefficiency by the 
introduction of forced draft under the grates. 
Thus by proper regulation the pressure in 
the furnace becomes equal to the atmos- 
pheric pressure outside, so that the detri- 
mental inrush of cold air while the doors are 
open is prevented, and the efficiency of com- 
bustion is largely increased. 

Another design of refuse destructor which 
was recently invented in this country by Dr. 
J. B. Harris is shown in Fig. 53. Provision 
is made for drying out the wet bulky mate- 
rial on water grates above the fire, these 
grates being formed by the upper tubes of a 
boiler constructed within the furnace. It is 
claimed that carcasses of dead animals can 
thus be effectively incinerated. 

Certain essential features are common to 
the most successful designs of refuse de- 
structors. They may be summarized as fol- 
lows : 

1. Very large combustion spaces or cham- 
bers are provided for checking the velocity 
of the gases and affording time for their 
diffusion with the air for combustion. 

2. The fuel is surrounded by hot fire- 
brick surfaces, the walls of which are capable 



PREVENTING POWER-PLANT LOSSES 




WASTE FUELS 465 

of retaining sufficient heat to gasify and 
canse the ignition of the fresh charge of fuel. 

3. The fresh charges are small in com- 
parison with the mass of burning refuse, in 
order to prevent the serious lowering of the 
furnace temperature. Necessarily, there- 
fore, the charging or firing is done at short 
intervals. 

4. An under-grate preheated forced draft 
of high intensity is employed to obtain (a) 
balanced furnace conditions, (b) an effective 
penetration of the mass of fuel, and (c) con- 
trolled combustion. 

5. Drying hearths or dead plates or other 
means are provided for evaporating the 
moisture from the refuse before it reaches 
the grate surface. 

6. A very important feature in operation 
is the mixing together of all the different 
classes of refuse to be destroyed. This pro- 
duces a constant supply of fuel of the aver- 
age calorific power for the furnace. Other- 
wise it would be easy to "kill" the fire by 
suddenly introducing a quantity of very wet 
or very bad refuse. 

7. Between one and two pounds of steam 
are generated for each pound of refuse de- 
stroyed, depending upon the composition of 
this refuse and upon the efficiency of design 
and operation of the destructor. 



4:66 PREVENTING POWER-PLANT LOSSES 

8. It has been found best from the stand- . 
point of efficiency as a general rule not to 
sort and pick the refuse but to let all go to 
the destructor. The picking of refuse is un- 
sanitary for the workers and dangerous, 
owing to possibility of contagious disease. 

There are still other substances which 
could be treated as waste fuels, but their 
discussion would, in the mind of the reader, 
merely emphasize the variety of methods 
used to apply the same principles of combus- 
tion. 

In summing up this broad subject of waste 
fuels, the author can only refer once more to 
the three simple requirements of combustion 
which apply to all fuels. 

1. High temperature. 

2. Correct air supply. 

3. Complete mixture of this air with the 
fuel gases. 

These combustion requirements are com- 
mon to all fuels— rich or poor in heat values, 
good or bad in physical or chemical compo- 
sition. The solution of any specific problem, 
the burning of any specific fuel, depends 
upon the scientific application of these com- 
mon requirements to the particular material 
in question. This belongs to the field of sci- 
entific design and operation of furnaces. 
That much advance has been accomplished in 



WASTE FUELS 467 

recent years in this field is demonstrated by 
the production of useful power-generating 
combustion with matter that had previously 
been considered either worthless as fuel or as 
belonging to the semi-combustible class which 
required the burning of expensive fuel for 
its ignition. 

It must be remembered, however, that such 
fuels intrinsically contain more heat units 
than are actually required for the mainte- 
nance of their gasification and ignition. If 
they did not, to burn them would be as im- 
possible as to make a stream run up hill. If 
they do contain a sufficient excess of heat 
over and above the gasification and ignition 
requirements, then the efficiency of their com- 
bustion depends entirely upon the design and 
operation of the furnace. 

Many quotations are made in text and ref- 
erence books as to the heat value of moist and 
fibrous fuels which are entirely misleading 
if not useless. This is owing, in the first 
place, to the variety of ways in which heat 
values may be reported and the absence in 
such quotations of definite specifications as 
to which of four different methods is used. 
Further — and equally serious — error may 
arise from dependence for calorific powers 
on formulas like Dulong's, which assume 
that all of the oxygen in a fuel is combined 



468 PREVENTING POWER-PLANT LOSSES 

before combustion with the hydrogen in that 
fuel. The error may be slight in fnels con- 
taining but little oxygen, but increases to 
serious extent with woody and many other 
waste fuels high in oxygen. Calculations 
containing this common error are unsafe and 
useless, both for comparison of combustion 
performances and for predicting results in 
any problem dealing with these fuels. 

As a final statement concerning the suc- 
cessful treatment of waste fuels, perhaps the 
most specific and at the same time the most 
general conclusion would be the following : 

As physical human beings are governed by 
the laws of hygiene common to all, so all 
waste fuels must be treated under the nature- 
determined laws of combustion common to 
fuels of every description; and likewise, 
there being no one medicine or treatment 
that will give perfect health to all persons, 
each individual requiring specific treatment 
according to his special condition, so also 
each particular waste fuel constitutes a spe- 
cific problem of its own and requires special 
study and treatment according to its own pe- 
culiar chemical and physical characteristics. 



Chapter XVII 

BOILER-FEED PUMPS; STEAM CONSUMP- 
TION TESTS 

T? OR supplying water to the boilers the di- 
^ rect-acting type of steam pump is almost 
universally employed. 

In the design of an efficient power plant 
the amount of exhaust steam to be produced 
must be estimated, and yet there are but few 
data in the form of actual tests on feed 
pumps available for such use. The most con- 
venient form of expressing the steam con- 
sumption of a feed pump is in a percentage 
of the total steam developed by the boilers 
which are served by the pump in question, 
and I have made careful tests to determine 
this value under working factory conditions 
in two places. These tests are given below. 

FEED-PUMP STEAM CONSUMPTION 

Test No. 1, June 3, 1913 

Make of pump Snow 

Type of pump Duplex 

469 



470 PREVENTING POWER-PLANT LOSSES 

Size of pump 6X4X6 

Size of feed line 2 inch 

Duration of test V/2 hrs. 

Exhaust from pump condensed in tank 

and condensation measured. 

Steam pressure in boiler 115 lb. 

Number of boilers served 2 

Temperature of feed water (approximate) 185 degrees 

Water fed by pump to boiler (total) 8,330 lb. 

Steam condensed from pump exhaust, 

total 552 lb. 

Per cent of boiler output used by feed 

pump, 552 -=- 8,330 6.63 

Boiler horse power developed at 30 lb. 

steam per horse power per hour 185 

Boiler horse power used by pump @ 30 

lb. steam per horse power per hour .... 12 . 25 

Conditions 

This was an old pump, its exact age not be- 
ing known. When the valve on the discharge 
line was closed and Ml steam pressure ad- 
mitted to the steam cylinders the pump 
showed a very small amount of slip in the 
water end and a comparatively small amount 
of leakage past the steam valves and the 
steam piston, all of which indicate that the 
pump was in average working condition when 
tested. Consequently this test may be taken 
as a fair indication of the amount of steam 
consumed by a duplex feed pump when han- 
dling two boilers under conditions of opera- 
tion corresponding to those existing in this 
plant. 



BOILER-FEED PUMPS 471 

It should be further noted that the pump 
was being regulated by a feed-water regula- 
tor and not by hand. The regulator when off 
did not quite stop the action of the pump, but 
allowed it to run very slowly so that it would 
scarcely discharge any water to the boilers 
during the off-time of the regulator. The 
pump would run about 1 minute or 1% min- 
utes at full speed and then the regulator 
would be off for about two to three minutes. 

Another condition of operation which 
should be noted is that the pump was taking 
cold water from measuring barrels having 
close connection to pump and forcing this 
water through a short length of pipe and 
thence through a Eeilly multicoil heater and 
from there to the boilers with an average 
number of turns in the feed piping which was 
2-inch. 

Method of Testing 

During the test all water fed to the boilers 
was measured in a feed-water weigher tested 
to within J^ of one per cent accuracy. The 
exhaust pipe of the feed pump was turned 
directly below the surface of cold water in a 
calibrated tank and so condensed. The 
weight of condensation was calculated from 
the increase in volume of the water, with 



472 PREVENTING POWER-PLANT LOSSES 

proper consideration of volume change due 
to the increased temperature at the end of 
the test. 

FEED-PUMP STEAM CONSUMPTION 

Test No. 2— July 10, 1913 

Make of pump 

Type of pump Duplex 

hand reg. 

Size of pump 4^X3X5 

Size of feed line 

Duration of test 2 hr. 37 min. 

Steam pressure in boiler 50 lb. 

Number of boilers served 2 

Temperature of feed water 68 degrees 

Water fed by pump to boiler 11,700 lb. 

Water fed by pump to boiler per hour . . 4,475 lb. 
Steam condensed from pump exhaust, 

total 684 lb. 

Per cent of boiler output used by feed 

pump 5.84 

Boiler horse power developed at 30 lb. 

steam per horse power per hour 149 

Boiler horse power used by pump @ 30 

lb. steam per horse power per hour .... 8.7 

Conditions 

This pump was an old second-hand one. It 
took water at 68 degrees and discharged it 
through a Berryman closed feed-water heat- 
er and about 50 feet of pipe into two horizon- 
tal tubular boilers. The general conditions 
of piping, number of turns, and general oper- 



BOILER-FEED PUMPS 473 

ation might be called average for small fac- 
tory power plants. The pump was regulated 
by hand, and drew its supply from a sump 
tank or barrel, the water level in which was 
about 18 inches above the level of the pump 
suction. 

Method of Testing 

The method of testing was precisely the 
same as that employed in test No. 1. (See 
pages 469, 470.) 

The steam consumption of a feed pump 
will depend upon the mechanical and thermal 
efficiency of the pump itself under the im- 
posed conditions of steam pressure, back 
pressure, and load, and upon the total head 
under which it works. These conditions will 
vary considerably, but a direct-acting steam 
pump is at best the most inefficient type of 
steam motor, and should be used only where 
steam economy is of secondary importance 
or where the exhaust steam can be thorough- 
ly utilized, as for instance in a feed-water 
heater or in the steam coils of a heating sys- 
tem. 

In any event the foregoing tests have their 
peculiar value as being based on no theoret- 
ical considerations whatever, but upon actual 
performance under the stated conditions ; and 
these results will serve well as a basis of 



474 PREVENTING POWER-PLANT LOSSES 

computation for the amount of exhaust to be 
ca^ed for in the layout of many small-sized 
factory plants. In such it may be safely 
figured that from 5 to 7 per cent of the total 
boiler steam will be required to operate the 
feed pump when the latter is of the direct- 
acting duplex type. The single-cylinder 
steam pump will take a little less steam than 
the duplex, owing to slightly less cylinder 
condensation, a less percentage of clearance, 
and less friction of pistons, rods and valves. 
The single pump on the other hand in usual 
designs is not so nearly positive in the actu- 
ation of its steam valves. 

The following calculation of efficiency will 
prove interesting as applied to the pump of 
test No. 1, this one being selected as being 
representative of a better average condition 
as to steam pressure on the boilers, i. e., 115 
pounds per square inch. 

Assuming the total head against which the 
pump was working to have been 120 pounds 
(allowing for lift to boilers and friction of 
piping, elbows and valves), the theoretical 
horse power of pumping would be 

HP =5^ 

33,000' 

in which 

W = Weight of water per minute = 92.55 

H = Height of lift = 120 X 2.3094 = 277.1 ft. hd. 



BOILER-FEED PUMPS 475 

T , ,. , , 92.55 X 277.1 A m 

Iheoretical horse power = =0.777 

oojUUU 

horse power 

That is, the actual work of moving the wa- 
ter at the above rate without loss was 0.777 
horse power. From the pump test 552 -=- 1.5 
= 368 pounds of steam per hour were ac- 
tually required to do this work. Hence the 
steam consumed per utilized horse-power 
hour was 368 -f- 0.777 = 473 pounds. 

Now if the mechanical efficiency of the 
pump is 50 per cent (see Kent) the indicated 
horse power of the pump was 0.777 -r- 0.50 
= 1.554 indicated horse power and the steam 
consumption of the pump per indicated horse 
power per hour was 237 pounds. 

A pound of steam at the boiler pressure 
contained 1,191 B.t.u. above 32 degrees F. 
and 237 pounds would contain 282,267 B.t.u. 
The heat equivalent of a mechanical horse- 
power hour is 2,545 B.t.u. Therefore the 
thermal efficiency of the pump referred to in- 
dicated horse power would be 2,545 -f- 282,267 
= 0.9 per cent. 

The thermal efficiency referred to the en- 
ergy actually utilized in moving the water 
would be one-half of this figure, i. e., 0.45 per 
cent. The efficiency of an engine using 30 
pounds of steam at this pressure referred to 



476 PREVENTING POWER-PLANT LOSSES 

actual or brake horse power would be 2,545 
~- (30 X 1,191) =7.12 per cent. 

Therefore we may say that the pump op- 
erated at an efficiency of 0.1263 or about % 
of the above engine efficiency when referred 
to indicated horse power, and at about 1/16 
of this engine efficiency when referred to util- 
ized energy. 

The following test on the steam consump- 
tion of a duplex feed pump made by Mr. S. 
Milton Clark, M. E., is interesting as addi- 
tional data checking closely the results ob- 
tained by the author on the two other tests 
quoted in this chapter. The conditions of 
this test were the same as those prevailing 
in the other tests on feed pumps quoted here- 
with. That is to say, the water fed to the 
boiler was obtained by actual weights and 
the exhaust from the pump was condensed 
and weighed. 

FEED-PUMP STEAM CONSUMPTION 

August 30, 1912 

Make of pump Fairbanks- 
Morse 

Type of pump Duplex 

Size of pump 6X4X6 

Size of feed line 

Duration of test 7 hours 

Steam pressure in boiler 89.06 lb. 

Number of boilers served 1 



BOILER-FEED PUMPS 477 

Temperature of feed water 185.2 de- 
grees F. 

Water fed by pump to boiler." 19,520 lb. 

Steam condensed from pump exhaust, 

total 1,145 lb. 

Per cent of boiler output used by feed 

pump 5.87 

Boiler horse power developed at 30 lb. 

steam per horse power per hour 93 

Boiler horse power used by pump @ 30 

lb. steam per horse power per hour .... 5.45 



Chapter XVIII 

■MODERN TYPES OE PRIME MOVERS 

/ T^HE old-fashioned portable slide-valve 
-*- engine monnted npon its own boiler and 
used largely for driving small temporary 
saw-mills and for similar light service con- 
sumed in the neighborhood of 8 to 10 ponnds 
of coal or its equivalent per brake horse- 
power hour. Fig. 54 illustrates this familiar 
device. 

Modern designs of engines mounted upon 
their boilers in Germany are recorded to 
have produced a brake horse-power hour for 
less than one pound of coal. Messrs. E. Wolf 
of Magdeburg, Germany, may be said to be 
the original developers of this type of unit, 
known on the continent as the ' l locomobile. ' \ 
Other European makers are now supplying 
the increasing market for these remarkable 
machines. It is stated that in Germany one 
firm alone has built nearly 1,000,000 horse 
power of these units. 

478 



MODERN PRIME MOVERS 



479 



The Locomobile 

The locomobile consists essentially of a 
very efficient type of condensing or noncon- 
densing engine mounted upon an internally 




Fig. 54. Regular Type op Portable Engine 



fired high-pressure boiler generating highly 
superheated steam. The compound-engine 
cylinders are jacketed in the flow of the hot 
flue gases on their way to the stack, to reduce 
cylinder condensation and radiation. The 
exhaust steam from the high-pressure cylin- 
der passes through a special superheater 



480 PREVENTING POWER-PLANT LOSSES 




MODERN PRIME MOVERS 481 

before returning to the low-pressure cylin- 
der. A closed feed-water heater returns some 
of the heat of the exhaust steam to the boiler. 

A locomobile type of self-contained unit is 
now manufactured in the United States and 
is known as the " Buckeyemobile. ' ' It is 
made in sizes from 75 horse power to 600 
horse power. Fig. 55 shows this machine in 
the tandem compound condensing design. 
Fig. 56 shows the internal parts and gives a 
clear idea' of their operation. 

As regards low fuel consumption, the lo- 
comobile type of steam plant competes on an 
equal basis with producer-gas plants and has 
in its favor the added advantage of the 
greater reliability of steam-driven as com- 
pared to gas-driven engines. 

It is further of interest to note that the 
high over-all efficiency of the locomobile type 
of plant is obtainable in spite of an ordinary, 
rather than with the aid of a high, boiler and 
furnace efficiency. If we could apply the 
Bone system of surface combustion (with oil 
or gas) to the locomobile, its over-all effi- 
ciency 1 would be increased by more than 18 

1 Efficiency of locomobile boiler taken at 70 per cent which would repre- 
sent favorable conditions of coal and firing. Efficiency of Bone boiler 
taken at 83 per cent — see chapter on Surface Combustion. Then gain of 

over-all efficiency would be — ^ — =18.6 per cent, and the saving of 
fuel for the same output would be — — — =15.7 per cent. 



482 



PREVENTING POWER-PLANT LOSSES 




MODERN PRIME MOVERS 483 

per cent and for the same output a saving of 
fuel (heat units) amounting to nearly 16 per 
cent would result. Moreover, the capacity of 
the locomobile would be multiplied by about 
five, so that it would be practicable to in- 
crease the size of the prime mover to a 
point where a steam turbine would give econ- 
omy equal to that of a reciprocating engine. 
It is altogether likely that development 
along these lines will take place with a view 
to use in localities where oil or gas is avail- 
able. The further extension of this idea for 
coal burning depends upon the questions out- 
lined in the chapter on Surface Combustion. 

These considerations are purely prophetic 
in character, but we need not anticipate fu- 
ture improvements in order to realize that 
the small 400 horse-power to 600 horse-power 
locomobile units as now constructed in this 
country equal the performance in low fuel 
consumption of the most refined and largest 
central steam-power stations ever designed. 
In fact, these small units are able to show 
coal economies which exceed the results reg- 
ularly obtained in highly refined central sta- 
tions of 50 to 200 times their capacity. 

Thus a small manufacturer may generate 
his own current at the same fuel expense per 
kilowatt hour as it costs the public utility 
corporation. This is omitting any consider- 



484 PREVENTING POWER-PLANT LOSSES 

ation of the use of exhaust steam when con- 
densing water is available. 

The following test on a 150 horse-power 
Buckeyemobile was made by Professor Thos. 
G. Estep of the mechanical-engineering de- 
partment of Carnegie Institute. In the ex- 
amination of this test it should be remem- 
bered that it was on one of the smaller size 
machines and that still better economy would 
be expected on a larger unit. 

OBSERVED AND CALCULATED RESULTS OF TEST 

General 
Total heating surface of boiler, sq. ft . . . . 350 . 
Heating surface in service during test, 

sq. ft 250.0 

Grate surface, 2 ft. 6 in. by 3 ft. in., or 

sq. ft 7.5 

Ratio of grate surf ace to heating surf ace . 1 to 33.3 

Superheating surface, sq. ft . . . -. 257 . 

Reheating surface, sq. ft 96 . 

Size of engine 8J^ in. by 

17 in. by 18 in. 

Rated horse power of engine 150 . 

Duration of trial, hours 8.0 

Kind of fuel Low-grade Pocahontas run-of-mine 

Kind of draft induced 

Average Pressures 
Steam pressure in boiler lb. per sq. in. 

gage 220.0 

Barometer, inches of mercury 28 . 85 

Absolute steam pressure, lb. per sq. in. . . 234. 1 

Receiver pressure, lb. per sq. in. gage 9.0 

Absolute receiver pressure, lb. per sq. in . . 23 . 1 



MODERN PEIME MOVERS 485 

Vacuum referred to 30 in. barometer, 

inches of mercury 25 . 

Absolute condenser pressure, inches of 

mercury 5.0 

Absolute condenser pressure, lb. per sq. in. 2 . 45 

Draft in furnace, inches of water 0.10 

Draft in breeching, inches of water 0.31 

Average Temperatures, in Degrees Fahrenheit 

Temperature of steam at throttle 595 . 

Saturation temperature at throttle 395 . 2 

Superheat at throttle 199. 8 

Temperature high-pressure exhaust 271.0 

Saturation temperature of high-pressure 

exhaust 235 . 7 

Superheat in high-pressure exhaust . . 35.2 

Temperature of steam leaving reheater. . . 367 . 

Superheat to low-pressure cylinder 131 .3 

Temperature of low-pressure exhaust. . . 132.0 
Saturation temperature of low-pressure 

exhaust 132.0 

Superheat in low-pressure exhaust none 

Temperature of feed water entering 

heater ; 108.0 

Temperature of feed water leaving heater 126 . 

Temperature of gases leaving boiler .... 736 . 

Temperature of gases in breeching 419.0 

Temperature of injection water to con- 
denser 96 . 

Temperature of overflow from conden- 
ser 114.8 

Temperature of fire room, approximately 80 . 

Flue-Gas Analysis, in Percentage by Volume 

Carbon dioxide 11.3 

Carbon monoxide . 24 

Oxygen 5.6 

Nitrogen 82.86 



100.00 



486 PREVENTING POWER-PLANT LOSSES 

Miscellaneous Averages 

Speed of engine, revolutions per minute . 225 . 
Indicated horse power in high-pressure 

cylinder 74 . 1 

Indicated horse power in low-pressure 

cylinder 55 . 6 

Total combined indicated horse power . . 129 . 7 

Brake horse power 125 . 5 

Mechanical efficiency of engine, per cent. 96 . 8 
Proximate Coal Analysis 

Moisture, per cent 2. 21 

Volatile matter, per cent 15 . 55 

Fixed carbon per cent 69 . 89 

Ash, per cent 12 . 35 

Sulphur, per cent . 48 

Ultimate Analysis 

Carbon, per cent 78 . 06 

Hydrogen, per cent 3 . 88 

Nitrogen, per cent . 94 

Oxygen, per cent 3 . 98 

Ash, per cent 12 . 64 

Sulphur, per cent . 50 

B.t.u. per pound of dry coal 13,541 

Total Quantities 

Total water fed to boiler, lb 11,430 

Moisture in steam assumed, per cent ... 1.5 

Quality of steam, per cent 98 . 5 

Total water actually evaporated by 

boiler, lb ..."...-.. 11,258.5 

Factor of evaporation, boiler alone 1 . 1403 

Factor of evaporation, boiler and super- 
heater r 1.3015 

Equivalent evaporation from and at 212 

degrees F., by boiler alone, lb 12,838 

Equivalent evaporation from and at 212 

degrees F., by boiler and superheater, lb 14,653 

Total coal as fired, lb 1,397 

Moisture in coal, per cent 2.21 



MODERN PRIME MOVERS 487 

Total dry coal used, lb 1,366. 1 

Ash from test, lb 87 . 

Ash from test, per cent 6 . 37 

Ash by analysis, per cent 12 . 35 

Total combustible (based on ash from 

analysis) lb 1,197 . 4 

Hourly Quantities and Rates 

Water fed to boiler per hour, lb 1,428. 8 

Water actually evaporated by boiler per 

hour, lb 1,407.3 

Equivalent evaporation from and at 212 

degrees F. per hour by boiler alone, lb. 1,604 . 8 

Equivalent evaporation from and at 212 
degrees F. per hour, by boiler and 
superheater, lb . . 1,831 . 6 

Boiler horse power developed by boiler 

alone 46 . 6 

Boiler horse power developed by boiler 

and superheater 53 . 2 

Coal as fired per hour, lb ........ 174 . 6 

Dry coal per hour, lb 170 . 8 

Combustible per hour, lb 149 . 7 

Water actually evaporated by boiler per 

sq. ft. of heating surface per hour .... 5 . 63 

Water evaporated from and at 212 de- 
grees F. per sq. ft. of heating surface 
per hour, lb 6 . 43 

Water actually evaporated by boiler per 

sq. ft. of grate surface per hour, lb 187 . 8 

Water evaporated from and at 212 de- 
grees F. by boiler per sq. ft. of grate 
surface per hour, lb 214 . 

Dry coal per sq. ft. of grate surface per 

hour, lb 22.8 

Dry coal per sq. ft. of heating surface per 
hour, lb 0.68 

Combustible per sq. ft. of grate surface 

perhour,lb " 20.0 



488 PREVENTING POWER-PLANT LOSSES 

Combustible per sq. ft. of heating surface 
per hour, lb 0.6 

Economic Results 
Water actually evaporated by boiler 

alone per pound of dry coal, lb 8 . 25 

Water actually evaporated by boiler 

alone per pound of combustible, lb ... . 9 . 40 

Equivalent evaporation from and at 212 

degrees F., by boiler alone per lb. of 

dry coal, lb 9.4 

Equivalent evaporation from and at 212 

degrees F., by boiler alone per lb. of 

combustible, lb 10.72 > 

Equivalent evaporation from and at 212 

degrees F., by boiler and superheaters 

per lb. of dry coal, lb 10.72 

Equivalent evaporation from and at 212 

degrees F., by boiler and superheaters 

per lb. of combustible 12 . 22 

Dry coal per boiler horse-power hour, 

boiler alone, lb 3 . 66 

Dry coal per boiler horse-power hour, 

boiler and superheaters, lb 3 . 21 

Combustible per boiler horse-power hour, 

boiler alone, lb 3 . 21 

Combustible per boiler horse-power hour, 

boiler and superheaters, lb 2 . 82 

Coal as fired per i.h.p. of engine per 

hour, lb... 1.'35 

Dry coal per i.h.p. of engine per hour, lb. . 1 . 315 

Coal as fired per b.h.p. of engine per hour, 

lb 1.39 

Dry coal per b.h.p. of engine per hour, lb. . 1 . 36 

Combustible per i.h.p. of engine per hour, 

lb 1.15 

Combustible per b.h.p. of engine per hour, 

lb 1.19 

Steam per i.h.p. per hour, lb 11 . 00 



MODERN PRIME MOVERS 



489 



Steam per b.h.p. per hour, lb 11 . 38 

B.t.u. in coal supplied to engine per i.h.p. 

hour 17,820 

B.t.u. in coal supplied to engine per b.h.p. 

hour 18,420 

Efficiencies 
Heating value per pound of dry coal 

B.t.u 13,541 

Heating value per pound of combustible 

B.t.u 15,500 

Efficiency of boiler, furnace and grate, 

per cent 

Efficiency of boiler, superheaters, furnace 

and grate, per cent 

Thermal efficiency of engine based on 

i.h.p., per cent 

Thermal efficiency of engine based on 

b.h.p., per cent . 

Thermal efficiency of entire unit, per cent 
Efficiency of engine referred to the Ran- 

kine Cycle efficiency as unity 

Mechanical efficiency of engine, per cent 



67 


2 


76 


5 


17 


05 


16 
13 


50 

8 


60.0 
96.8 



Boiler Heat Balance 


B.t.u. 


Per cent 


Heat absorbed by boiler and su- 
perheaters per lb. of combus- 
tible 


11,897.0 

31.0 

420.0 

189.0 

1,920.0 
1,043 
15,500.0 


76.82 


Loss due to moisture in coal per 
lb. of combustible 


0.20 


Loss due to hydrogen in the coal 
per lb. of combustible 

Loss due to incomplete or CO per 
lb. of combustible 


2.72 
1.23 


Loss due to chimney gases per lb. 
of combustible 


12.28 


Radiation and unaccounted losses 
B.t.u. per lb. of combustible 


6.75 



490 PREVENTING POWER-PLANT LOSSES 

The curves charted in Fig. 57, submitted 
by the Buckeye Engine Co., will serve to il- 
lustrate the relations of steam and fuel con- 
sumptions at various loads on a 150 horse- 
power Buckeyemobile. 

Engineers have criticized as detrimentar 
to the boiler the* element of vibration com- 
municated to it by the superimposed engine. 
As far as any published record of trouble 
goes there seems to be at present no evidence 
that the boiler is materially injured in the 
locomobile. 

Unaelow Steam Engine 

The unaflow engine invented by Professor 
J. Stumpf of Charlottenburg Hochschule 
marks a notable advance in the design of 
prime movers. As its name indicates, the 
steam from its entry to its exhaust flows in 
only one direction on either side of the pis- 
ton. The idea of the invention is to produce 
the economy of a compound or triple-expan- 
sion steam engine by means of a simple sin- 
gle-cylinder engine, and this result has been 
achieved. The working of the engine in- 
volves a very early cut-off, a high compres- 
sion, and a graduated distribution of tem- 
perature from admission to exhaust. The 
engine is primarily designed for high pres- 



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} HORSE-POWBK BuCKEYEMOBILE. MAY 15-27, 1914 



MODERN PRIME MOVERS 491 

sure and at the same time highly superheat- 
ed steam, although remarkably high econo- 
mies are obtained with saturated steam, in 
which latter case the steam jackets are ex- 
tended over a greater portion of the cylinder. 
As will be recalled from the discussion on 
steam-engine losses in Chapter VI, maximum 
economy is obtained by dividing the work 
of expansion of the steam into several stages 
or cylinders, thus developing the compound, 
the triple- and quadruple-expansion engines. 
Compounding is efficient only with high-pres- 
sure steam, which for complete expansion in- 
volves a wide range of temperature from the 
high point at admission to the low point at 
exhaust. If this steam were expanded all in 
one cylinder this cylinder would be subject 
to these wide variations of temperature. 
Thus at exhaust the cylinder would be cooled 
to a point approaching the temperature of 
the exhaust steam. Then when the high-pres- 
sure steam is admitted, owing to this wide 
difference of temperature, a heavy cylinder 
condensation would result. Consequently 
compounding was resorted to so that the 
steam entering each of the various cylinders 
would come in contact with metal approach- 
ing its own working temperature. In this 
manner the great cylinder condensation 



492 



PREVENTING POWER-PLANT LOSSES 



which would occur in a single cylinder is 
greatly reduced. 

Professor Stumpf has produced a single- 




courtesy of Steam 
Fig. 58. Sulzer Bros. Stumpf Unaflow Engine 

cylinder engine, however, which, owing to its 
unaflow principle, maintains a graduated 
temperature in the cylinder walls and this 




Courtesy of Steam 

Fig. 59. Sulzer Bros. Stumpf Unaflow Engine 

temperature approximates the temperature 
of the steam in the cylinder at all parts of 
the stroke, so that the condensation is re- 



MODERN PRIME MOVERS 



493 



duced to zero in best practice and to a mini- 
mum in any case. Figs. 58 and 59 exhibit side 
views of a 500 horse-power Sulzer Brothers 
Stumpf engine. Fig. 60 shows diagram- 
matically the construction of the cylinder, 
piston and steam ports. It will be noted that 
the steam enters through the cylinder head 




Courtesy of Steam 

Fig. 60. Steam Flow in Sulzer Bros. Stumpf Unaflow 
Engine 

and that the steam chest so formed acts as 
a jacket for the head of the cylinder. This 
maintains a maximum temperature at that 
part of the cylinder where high pressure and 
only high pressure is active. The path of 
the steam, including its admission, expan- 
sion, and exhaust is indicated by the arrow 
in this figure. The steam follows through the 



494 



PREVENTING POWER-PLANT LOSSES 



stroke until the piston, which is of special 
hollow construction, opens the exhaust ports 
forming a belt surrounding the cylinder. 
Thus all exhaust valves are eliminated and 
consequently leakage from this source is 
reduced to a theoretical minimum. 




Courtesy of Steam 

Fig. 61. Condenser Connection and Indicator Diagrams 
Sulzer Bros. Stumpf Unaflow Engine 

A glance at the arrow above mentioned 
explains the name of "unaflow." In the or- 
dinary reciprocating engine the steam flows 
in two directions instead of one, and it ex- 
hausts at the same end of the cylinder from 
which it enters. Consequently the exhaust 
steam greatly reduces the temperature of 
that portion of the cylinder with which the 



MODERN PRIME MOVERS 495 

incoming hot steam will be in contact. This 
results in the great cylinder condensation, 
which frequently amounts to 25 per cent of 
the water consumption of the engine. 

In the unaflow engine when exhaust has 
taken place the piston returns covering the 
exhaust ports and immediately compression 
begins. This compression takes place during 
about 90 per cent of the entire stroke of the 
engine. Consequently the compressed steam 
reaches a temperature about equal to that 
of the boiler pressure. This high compres- 
sion, combined with the almost ideal admis- 
sion and expansion of the steam, produces 
an indicator card which approaches the ideal 
Carnot cycle and explains the very high effi- 
ciencies obtained by the unaflow engine. 

The piston is of special construction and 
is elongated so as to act as an exhaust valve 
in covering and uncovering the ports sur- 
rounding the middle section of the cylinder. 

The clearance in this engine is reduced to a 
minimum because there are no exhaust ports 
at the head end as in ordinary engines, and 
this fact results in adding to the general effi- 
ciency of the design. The condenser is close- 
ly connected to the annular exhaust chamber 
as shown in Fig. 61, permitting a maximum 
vacuum to be effected in the cylinder. 

When operating, if for any reason the vac- 



496 



PREVENTING POWER-PLANT LOSSES 



uum breaks the compression produced will 
be above boiler pressure, since the terminal 
density of the steam will be suddenly in- 
creased. To take care of this emergency the 
inlet valve will lift from its seat to relieve the 

-d — en 



XT 





Fig. 62. 



Courtesy of Steam 

Steam Jacketing of Unaflow Engine 



pressure back to the boilers. When starting 
up, an additional clearance space may be 
opened into the cylinder by means of a hand 
valve in order to prevent excessive compres- 
sion until full vacuum is established. This 
valve may also be made to operate automat- 



MODERN PRIME MOVERS 497 

ically in case of the breaking of the vacuum 
during operation. While the unaflow engine 
is primarily designed to take advantage of 
only high pressures and high superheat, it is 
also modified to produce very high efficiencies 
on saturated steam. This is accomplished 
by extending steam jackets (as shown in 
Fig. 62) so that they cover a greater sur- 
face of the cylinder in accordance with re- 
quirements. Thus in the top diagram of 
Fig. 63 only the cylinder heads are jacketed, 
and this design would be best adapted to 
highly superheated steam. The middle fig- 
ure shows the steam jacket extending over a 
part of the cylinder beyond the heads, and 
would be adapted for a lower temperature 
steam; while in the bottom diagram the jack- 
ets extend still further to produce economical 
operation with saturated steam. The pur- 
pose in any of these cases is to prevent cyl- 
inder condensation, but in all three provision 
is maintained for keeping the high-pressure 
end of the cylinder hot and the low-pressure 
end cooler, so that the steam at any part of 
the stroke is always at a lower temperature 
than the surrounding walls of the cylinder, 
which prevents transferring of heat from the 
steam to the metal. The unaflow engine is 
capable of very great overload capacity and 
also produces flat economy curves. In fact, 



498 



PREVENTING POWER-PLANT LOSSES 



the steam consumption per horse-power hour 
at wide variations of load varies less than 
with triple-expansion or compound engines. 




3rd Stroke 
Working Stroke 




4th Stroke 
Exhaust 




1. Intake. 

2. Compression 

3. Working Stroke. 
l 4. Exhaust. 




STROKE 

Courtesy of Busch-Sulzer Bros. Engine Co. 

Fig. 63 

Professor Stumpf has applied his engine to 
locomobiles (described in another section of 
this chapter), with highly efficient results, 
and to locomotives which have been widely 
adopted in Germany, Austria, and Eussia. 



MODERN PRIME MOVERS 499 

In marine practice it is claimed that one 
pound of coal lias produced an indicator 
horse-power hour on 500 horse-power en- 
gines. In stationary practice these engines 
have been built in capacities as high as 8,000 
to 10,000 horse power and are in successful 
operation. In this country we may expect a 
rapid growth in the utilization of the unaflow 
principle, and one firm at least is now en- 
gaged in the manufacture of this type of en- 
gine. The following test is taken from the lit- 
erature of John Musgrave & Sons, Ltd., Eng- 
lish manufacturers of the unaflow engine: 

A test made on this engine by the Elsassischen 
Verein der Dampfkesselbesitzer (the Union of the 
Steam Boiler Users of Alsace), in February, 1909, 
gave the following results: — 

Power 494 i.h.p. 

Cylinder 25}^ m - diameter 

Stroke 3 ft. 3 3/8 in. 

Speed -.' 130 r/p.m. 

Boiler pressure 178 lb. per sq. in. 

Superheat 250 degrees F. 

Vacuum in cylinder 26 in. 

STEAM CONSUMPTION PER I.H.P. PER HOUR = 10.38 LB. 

With 362 i.h.p. and 200 degrees F. superheat the 
steam consumption was 10.55 lb. per i.h.p. per hour. 

Oil Engines 

The Diesel and the De La Vergne repre- 
sent the most efficient types of internal-com- 
bustion engines designed to operate on oil. 



500 



PREVENTING POWER-PLANT LOSSES 




Courtesy of The Busch-Sulzer Bros. Diesel Engine Co. 

Fig. 64. A Diesel Engine 

Both work on the four--cycle principle which 
is clearly illustrated by the diagrams of Fig. 
63. Combustion occurs once in every four 
strokes or every two revolutions, thus : — 



MODERN PRIME MOVERS 501 

First stroke : intake of fresh air ; piston 
traveling outward. 

Second stroke: compression of this air; 
piston moving inward. 

Third stroke: injection of fuel at dead cen- 
tre, causing combustion and expansion of the 




Fig. 65. De La Vergne 90 Horse-power Oil Engine 



working stroke with piston moving outward. 

Fourth stroke : expulsion of exhaust gases 
from cylinder; piston moving inward. 

These events may be traced on the indi- 
cator diagram of the Diesel engine in the 
lower part of Fig. 63. Fig. 64 illustrates 
the Diesel engine and Figs. 65, 66 and 61 ap- 
ply to the De La Vergne. In both of the 



502 



PREVENTING POWER-PLANT LOSSES 




MODERN PRIME MOVERS 503 

above engines the oil is atomized and inject- 
ed into the cylinder by means of very highly 
compressed air. But the essential differ- 
ences in their operation are as follows : 

Compression. The Diesel compresses the 
fresh-air charge in the cylinder to 460 pounds 
per square inch; the De La Vergne to about 
300 pounds. 




Fig. 67. De La Vergne Vaporizer 

Ignition. The Diesel depends solely upon 
the temperature of the compression, about 
1,000 degrees F., to ignite the charge of oil 
as it is sprayed into this heated air. The 
De La Vergne also makes use of its temper- 
ature due to compression, which is lower, but 
does not depend solely upon this agency. It 
employs in addition the use of a vaporizer 
which is a modified form of hot bulb. This 



504 PREVENTING POWER-PLANT LOSSES 

serves the double purpose of insuring igni- 
tion and of completing the gasification of the 
oil which is sprayed against its hot surfaces. 
This vaporizer is shown in detail in Fig. 61 
and in its relation to the engine at D in Fig. 
66. 

Injection of Fuel. In both engines the oil 
enters the cylinder by the action of air under 
high pressure but small in volume. The De 
La Vergne injects its oil instantaneously, in 
charges measured out by a small oil pump 
connected to the engine and timed with its 
action. The Diesel introduces its oil in a 
spray which continues over a considerable 
period of time, covering ordinarily one-tenth 
to one-eighth of the stroke of the piston. 

Governing. In the De La Vergne the gov- 
ernor controls by a cam mechanism the length 
of stroke of the oil-supply pump and thereby 
causes it to measure out to the engine the 
exact amount per cycle which may be re- 
quired to maintain the regular speed of the 
engine for all variations of the load. 

The Diesel governor regulates the time 
period of injection according to load require- 
ments. Thus the oil will continue to enter the 
cylinder as the piston moves forward from 
dead centre as far as say 12 per cent of the 
stroke, or to such point as may be required 
to meet the load conditions. Thus this ef- 



MODERN PRIME MOVERS 505 

feet of fuel admission may be compared to 
the steam admission on a Corliss engine, and 
this together with the automatic and quick 
termination of the admission period results 
in an indicator diagram which strongly re- 
sembles that produced by this* type of steam 
engine. 

From the standpoint of thermal efficiency 
alone, highly developed oil engines of the 
above types are superior to any other class 
of prime movers. Their commercial effici- 
ency varies with, and depends upon, the cost 
and reliability of oil supply, the size and cost 
of plant, the character of service, and other 
determining values dependent upon local 
conditions. 

With the Diesel engine efficiencies as high 
as 32 to 35 per cent based on net useful out- 
put are claimed. With an oil of 19,000 B.t.u. 
per pound this would mean 0.42 pounds of 
fuel per brake horse-power hour. The char- 
acteristically "flat" economy curve of this 
engine is shown in Fig. 68. Efficiencies 
equal to these both at full and at partial 
loads are claimed for the De La Vergne en- 
gine. 

One of the greatest advantages of an oil- 
engine plant is that the prime mover alone 
constitutes an entire plant in itself. Gas pro- 
ducers or boilers are eliminated, and attend- 



506 PREVENTING POWER-PLANT LOSSES 

ance is reduced except in very small under- 
takings, and the factor of reliability of the oil 
engine approaches that of the steam plant. 
As compared to the gas engine in this respect 
the oil engine has two distinct advantages. 
The feeding of its fuel in accurately meas- 
ured amounts is positive, and for ignition of 
the charge it is not dependent upon electrical 
complications as is the gas engine. The re- 
liability of the oil engine is being demon- 
strated by the rapid increase of its applica- 
tion for marine use, where an important sav- 
ing of space and weight is also accomplished. 

The fuel cost of power with an oil engine 
depends upon the efficiency, the load factor 
and the price and B.t.u. of the available oil 
supply. Conditions representing good fac- 
tory practice would combine load factor, effi- 
ciency of engine and B.t.u. of oil such as to 
produce an average brake horse-power hour 
for about 0.6 pounds of oil. Assuming the 
cost of the oil to be $0,025 per gallon contain- 
ing 7% pounds, the fuel cost per brake horse- 
power hour will be 0.025 -:- 7.5 = $0.00333 
= Sys mills. If the oil cost $0.05 per gallon 
the fuel cost per brake horse power will be 
doubled. 

For marine purposes on a small scale a 
special carburetor has been devised which 
permits the use of kerosene in regular gaso- 



MODERN PRIME MOVERS 



507 



line engines, thus making available a cheaper 
fuel. This device has also been applied to 
automobile engines. The idea involved is the 
gasification of the less volatile fuel by the 
application of heat furnished by the exhaust 





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Courtesy of Busch-Sulzer Bros. Diesel Engine Co. 

Fig. 68. Diesel Fuel Consumption per Kilowatt Hour 
at Various Loads 



gases from the engine. The gas is then used 
in the engine in the ordinary manner. The 
troublesome electric ignition system is not 
eliminated, and the use of this style of oil 
engine has received little if any encourage- 
ment for factory power-plant application. 



Chaptee XIX 

EEPORTS 

A N owner's decision to have an investiga- 
-**• tion made in his plant is frequently 
brought about by one or more problems of 
specific nature which require immediate so- 
lution. The manner in which such a case is 
handled will often determine the whole op- 
erating economy of the plant during many 
years to come, either for better or for worse ; 
and in the long run will involve either con- 
tinuous items of efficiency and satisfaction or 
of waste and expense. 

I have chosen a case of this class by way 
of supplying definite answers to some of the 
concrete questions which our previous more 
or less abstract discussions may have pro- 
voked. Owing to space limitations these re- 
ports have been greatly abbreviated. But 
since the second contains a comparative rec- 
ord of operating economy after the recom- 
mendations of the first report had been car- 
508 



REPORTS 509 

ried out, it will be of particular interest, and 
more especially so because the questions 
treated are among those which confront ' 
many manufacturing plants at the present 
time. Probably no one case of investigation 
and improvement can be selected as typical, 
either as to saving effected or problems in- 
volved. The present instance contains a suf- 
ficient variety of questions, however, to claim 
at least the title of "average" from that 
point of view. 

The boiler plant was found to be highly 
efficient, an unusual occurrence in the course 
of my work; and cheap fuel was being used 
so that but little saving could be made at that 
point. Therefore, since practically all the 
economies had to be found in the remaining 
departments, the saving of $5,000 a year, 
based on operation during the acceptance 
tests, may be considered good under the cir- 
cumstances, especially in a plant of only 400 
boiler horse-power rating with small running 
expenses. 

The mill owners were under pressing need 
of more power owing to a rapid growth of 
their business. They had a good compound 
condensing engine supplied by two 6% by 
20-foot horizontal tubular boilers at 125- 
pounds pressure, with usual condenser, feed, 
and fire-pump equipment. Besides the steam 



510 • PREVENTING POWER-PLANT LOSSES 

power, they were purchasing additional elec- 
tric current at 2% cents per kilowatt hour. 
The mill was heated throughout, including a 
supply for process work, with live steam 
from the boiler reduced to 20-pounds pres- 
sure. The system comprised both direct and 
indirect heating. 

The management was progressive and effi- 
cient. This briefly comprised the situation 
when I was called into consultation. The 
problem in hand resolved itself into three 
specific questions which may be stated as fol- 
lows : — 

1. Should all future increase of power be 
provided by the purchase of outside electric 
current, leaving the steam plant to furnish 
its present amount of power ? 

2. Should the use of the present steam- 
power plant be discontinued entirely, and 
all the machinery of the mill be driven by 
purchased current? In this event the power 
company oiTered a rate of two cents per kilo- 
watt hour. 

3. Should the mill throw out all purchased 
current and make its own power exclusively, 
increasing its plant equipment for this pur- 
pose? If so, what style of plant would best 
meet these conditions'? 

In order to determine these questions in- 
telligently, it was necessary first to know at 



REPORTS 511 

what cost, all charges included, the present 
steam plant was making power. This conld 
not be learned without an investigation as to 
the amount of live steam used for heating, 
since this item would directly determine that 
portion of the boiler-plant overhead and la- 
bor expenses which would be chargeable ex- 
clusively to heating. Special tests for this 
purpose were planned and conducted. 

It was also desired to learn at what cost 
per kilowatt hour all the power could be 
made with added and improved steam equip- 
ment. 

Since a large portion of this item would 
be inversely proportional to the amount of 
power required during the year, special tests 
were made in order to obtain the twenty- 
four-hour load curves both of the present 
engine and of the power furnished by the 
purchased current. 

The results of all the tests that were made 
both on the steam and electric power were 
carefully checked up with the company's rec- 
ords of cost for fuel, labor, repairs, interest 
charges, and expenditures for the purchased 
current. This is a most essential procedure 
in all investigating work, in order that the 
total power output per year may be accurate- 
ly obtained to insure substantial correspond- 
ence of factory records with the actual test 



512 PREVENTING POWER-PLANT LOSSES 

results, and to obtain a mathematically cor- 
rect figure on the increase in steam require- 
ments during the winter months. This work 
involves a thorough acquaintance with the 
methods employed by the book-keeping de- 
partment of the business and a most careful 
analysis of the data on record. It has to be 
remembered that the head book-keeper does 
not pretend to be an engineer, and his data 
usually require the most painstaking analy- 
sis by the investigator in order to divide the 
expenses into the particular items applicable 
to the work in hand. 

In this instance the available records were 
unusually complete and clear, and it was pos- 
sible to save much time in this part of the 
work. There was no difficulty in enlisting 
the interest and help of the power-plant op- 
erating force, and this fact proved of great 
value in arranging for and conducting the 
various tests which are recorded. 

For convenience to the executives of a 
business I set down my recommendations and 
findings in a condensed form at the head of 
my report, so that the gist of the matter 
may be found within a few pages. The rec- 
ords of all tests and the complete data to sub- 
stantiate these conclusions are then given in 
full and properly indexed for quick refer- 
ence. Other matters than those outlined 



513 



were also taken up in these reports, bnt many 
of them are omitted for the sake of simpli- 
fication and of direct dealing with the prin- 
cipal problems involved. 

A little story connected with these reports 
which are to follow does not appear within 
their pages. Before I was called in, one of 
the large electric manufacturing companies 
was requested to send an engineer to make 
an examination of the power situation at the 
mill for the purpose of reporting recommen- 
dations to suit the case in hand. 

This they did, and their report called for 
an expenditure for steam and electric ap- 
paratus, which they specified, amounting to 
$40,000. 

My report for accomplishing the desired 
result, which was put into effect, called for an 
outlay of only $7,000, including installation, 
with this difference: my plan provided for 
the utilization of exhaust steam ; their plan 
did not. In the execution of the adopted plan 
the electrical machinery was purchased from 
this same company, but my client saved 
$33,000 in first cost. Many morals might be 
drawn from this little incident, but their de- 
duction may as well be left to the reader. 

As far as possible in these reports I have 
omitted those sections of each which appear 
to be treated in the other to a sufficient ex- 



514 PREVENTING POWER-PLANT LOSSES 

tent to inform the reader, at least by im- 
plication, of all the important features un- 
der examination. 

The net dividend on the investment of 
$7,000 was found to be over $5,000 per year, 
as shown in the second report, thus produc- 
ing returns to my clients of 71% per cent per 
annum on their outlay of capital. 



INVESTIGATION AND REPORT ON STEAM 

AND FUEL CONDITIONS AND 

COST OF POWER 

DIVISIONS OF THE REPORT 

Page 

Object and Method of the Investigation 515 

Recommendations 517 

Steam for Mill Requirements — Three Tests. . . 519 

Steam Used at Night— All Night Test 521 

Efficiency Test of Boiler Plant 523 

Flue-Gas Analyses 523 

Costs of Evaporation 529 

Boiler-Plant Capacity 530 

Boiler-Plant Efficiency 531 

Power-Plant Operating-Cost Sheet 534 

Cost of Power with Present Equipment 535 

Efficiency of Main Engine, All-Day Test 540 

Capacity of Main Engine 541 

Electric Power-Cost of Making versus Buying . 542 

Electric Power Required 544 



515 



OBJECT AND METHOD OF INVESTIGATION 

The principal object of the tests made at. this 
plant was to determine the following questions: — 

1. Would it be economical to discontinue the 
present steam-power plant and buy all the power 
required to run the mill, at the rate of 2 cents per 
kilowatt-hour? 

2. Would it pay to continue the present steam 
plant for present requirements (as now carried by 
said plant) and depend upon purchased electric 
power for all additional requirements and for in- 
crease of power at 2 1 /} cents per kilowatt hour? 

3. Would it pay for this plant to discontinue buy- 
ing electric power and enlarge the present plant to 
make all the power required ; and if so, what kind 
of equipment would best suit the local conditions 
for highest commercial efficiency? 

The following tests furnished basic information 
in the investigation and determination of these 
questions : — 

a. Day and night loads on the boiler plant. 

b. Day and night loads on the engine plant. 

c. Day and night loads on the purchased electric 
power. 

d. The efficiency of boiler plant and engine plant, 
both separate and combined. 

e. The amount of steam or boiler horse power re- 
quired for heating and mill-process work as compared 
to the steam used in the engine. 

f. The costs of evaporation both with the usual 
mixture of dust and slack, and with slack alone. 

g. Comparison of electric versus shafting and 
belting drive from present engine, etc. 

The method of testing was to take conditions 
exactly as found, the engineer and fireman being 



516 PREVENTING POWER-PLANT LOSSES 

asked to continue their duties in every way exactly 
as though the writer was not on the premises. A 
constant effort was made to maintain these actual 
working and not test conditions. 

CONCLUSION 

The final result of this investigation has shown in 
a very decided manner that the most economical 
solution is for this plant to make all its own power 
and discontinue buying electric power. 

Present Plant. — The present engine plant is mak- 
ing power at the rate of $0.0132 per kilowatt per 
hour, even when the engine is running below its 
normal capacity. If .the engine is speeded up 10 per 
cent and run at an average of 300 horse power, a 
kilowatt hour would be produced for $0.00971. 

Cost per Kilowatt Hour. — These costs include 
all charges against power, such as depreciation, 
interest, operating and fuel cost, all having been 
based on actual tests and data from the company's 
books. 

Additional Power. — It has been shown by special 
tests and computation submitted herewith that this 
plant can install a new electric generator set and 
make all the electric power now purchased (at 2% 
cents) for $0.01238 per kilowatt hour with the 
present load, and for about $0,009 when this load 
reaches 1,000 kilowatt hours per day. This is based 
upon the utilization of one-half of the exhaust 
steam from the new unit, a safe figure borne out by 
my tests. 

Saving. — Actually, however, the utilization of ex- 
haust steam will reduce the fuel per kilowatt hour 
to less than one-half, so that the above costs may 
be considered as high figures. There will be a sav- 
ing of at least 1.26 cents per kilowatt hour at the 
present light load, which amounts to $7.34 a day 



REPORTS 517 

when using the present amount, i. e., 582 kilowatt 
hours a day (average working days, 1908). l 

There will be a charge of 50 cents a day for de- 
preciation and interest on new exhaust apparatus, 
making the net saving $6.84 a day or $2,052 a year 
of 300 working days, with the present light load. 

The addition of the unit recommended will in- 
crease the present engine-plant capacity about 50 
per cent. 

Future Saving. — With the rapid growth of the 
plant now predicted it is safe to state that about 
1,000 kilowatt hours per day will soon be required 
instead of the 582 kilowatt hours now purchased 
from the A. & S. Power Co. When this occurs, 
your new unit will be making a kilowatt hour for 
about $0,009 as above stated, thus saving (0.025- 
0.009) =0.016 per kilowatt hour over the A. & S. 
Power Co.'s rates. This is $16 per day or $4,800 
per year. Or if the interest on heating apparatus 
be deducted, the net saving will be $4,650 per year. 

The saving will be still greater as time goes on. 
and the load increases. 

As an investment, based on the estimated saving 
a year hence, this company would receive 4,650 -h 
8,000 = 58 per cent net returns, all charges taken 
into account. 

RECOMMENDATIONS 

Continue Present Engine. — Continue the present 
steam plant and increase the available power by 
speeding engine up 10 per cent, i. e., to 95 revolu- 
tions per minute. 

Overhaul Engine. — Have the engine thoroughly 
overhauled and tuned up to reduce the steam con- 
sumption. 

1 This power consumption increased to 1,070 kilowatt hours, thus show- 
ing a correspondingly greater saving as per second investigation after 
recommendations were carried out, 



518 PREVENTING POWER-PLANT LOSSES 

New Unit Recommended. — Install a direct-con- 
nected simple Corliss engine and generator set for 
making the necessary electric power instead of buy- 
ing this power, this generating set to be run at 
night and usually in the day time except when the 
load on the main engine is running very light. 
Make this new set of 90-kilo watts rated capacity. 
It would then run at the present load at about one- 
third of its rated power, which would give an extra 
60 kilowatts of available power for increasing the 
factory load. 

This unit should be of as slow speed as possible 
i. e., in the neighborhood of 125 to 130 revolutions. 

Utilizing Exhaust. — It is recommended that the 
exhaust steam from this unit be used in the present 
heating fan and in the contemplated new heating 
fan for heating all parts of the mill, and also in a 
new and larger feed-water heater for raising the 
temperature of the boiler water. 

Vacuum System. — A vacuum return-line system 
is required to give proper circulation of the ex- 
haust steam in the fan coils. By extending this 
vacuum system to the office radiators x this engine 
exhaust could be used in heating the office as well. 

Night Man. — It is recommended that a good man 
be put on at night when the new engine is installed 
to look after same, and also to take charge of the 
boilers. Such a man would probably save 10 to 20 
per cent of coal for the same production of steam as 
at present. 

Bank One Boiler at Night. — With the small 
amount of steam used at night at the present time 
the boilers are run at only about 17 per cent of 
their rated power. Even if it is not thought ad- 
visable to shut off the steam from one boiler at 

i Both direct and indirect heating were employed. 



REPORTS 519 

night, one fire should be banked, and the damper, 
fire-doors and blower tubes kept tightly closed. 
Thus by making a single boiler do the whole work 
the rate of combustion would be doubled, a higher 
fire-temperature would be maintained, and less 
superfluous air would get through the grates to 
cool the boilers. This would result in a substantial 
saving. 

Separator and Receiver. — The new engine should 
have its steam pipe fitted with a combination re- 
ceiver and separator to supply the engine with dry 
steam and a uniform pressure. It would also tend 
to prevent vibration of the steam line. 



Steam for Mill Requirements 
three tests 

TEST NO. 1 

Rough Preliminary Test 

Evaporation of No. 1 boiler when supplying mill 
requirements alone, main engine being cut out. 
Test made in afternoon. 

Date Oct. 14, 1909 

Duration, hours 4 

Pounds evaporated 12,200 

Pounds evaporated per hour 3,050 

Steam gage, pounds 120 

Temperature of feed water, degrees F . . 161 

Factor of evaporation 1 . 0969 

Equivalent evaporation per hour 3,353 

Boiler horse power developed - 97 . 2 

Rated horse power of boiler at 12 sq. ft . 207 
Percentage of boiler horse power de- 
veloped 47 



520 PREVENTING POWER-PLANT LOSSES 

TEST NO. 2 

Second test on No. 1 boiler when supplying mill 
requirements only. 

Date. . Oct. 15, 1909 

Duration, hours 8 

Pounds evaporated 22,050 

Pounds evaporated per hour 2,756 

Steam gage, pounds 110 

Temperature of feed water, degrees F . 161 

Factor of evaporation 1 . 0951 

Equivalent evaporation per hour 3,017 

Boiler horse power developed 87 . 5 

Rated horse power of boiler 207 

Percentage of boiler horse power de- 
veloped 42.3 

In this test No. 1 boiler was shut off from the 
engine by the usual valves for the purpose but was 
not blanked off with flanges. Outdoor tempera- 
ture at 8 a.m. was 46 degrees. At 3 p.m. was 
53 degrees. The heating load during this test was 
as follows: Four felt dryers were on all day; part 
of the office steam on. Two coil dryers were on, 
but scouring room and big fan were off during the 
test. 

TEST no. 3 

Test No. 3 on steam used in mill line, steam line 
blanked off to mill only. 

Date Oct. 18, 1909 

Duration of test (9.35 a.m. — 5.05 p.m.) 

hours 7}^2 

Average steam pressure, pounds 110 

Average temperature of feed water, de- 
grees F 158 

Factor of evaporation 1 . 0982 

Total water evaporated, pounds 42,000 

Water evaporated per hour, pounds. . . 5,600 



REPORTS 521 

Water evaporated per hour from and 

at 212 6,150 

Average boiler horse power developed . 178 . 3 

Maximum boiler horse power developed 

(1 hour) 229 

Minimum boiler horse power developed 

(1 hour) 140 

Rated horse power of boiler 207 

Percentage rated horse power devel- 
oped (average) 86.2 

On this day 4,000 pounds of wool were scoured, 
(on some days 6,000 pounds are scoured) and all 
heating apparatus was on (except part of the office 
steam) including the large fan and the scouring room. 
During this test an estimate of the horse power was 
made each hour and found to be approximately as 
follows : 

Horse Power 
to Mill 

9.35—10.35 140 

10.35—11.35 229 

11.35—12.35 178 

12.35— 1.35 : 152 

1.35— 2.35 197 

2.35— 3.35 190 

3.35— 4.35 165 

4.35— 5.05 178 

The weather was warm, with rain all the after- 
noon. 

STEAM USED AT NIGHT 

A test of thirteen-hours duration was made from 
6 p.m. to 7 a.m. to determine the amount of steam 
made at night which is entirely consumed for heating 
purposes. 

Both boilers were run as usual and firei by the 
night-watchman. 



522 PREVENTING POWER-PLANT LOSSES 

Results of Test 

Date Nov. 3 &4, 1909 

Duration, hours 13 

Water evaporated, pounds 28,764 

Water evaporated per hour, pounds. 2,213 

Temperature of feed water, degrees F 154 

Steam gage, pounds 105 

Water evaporated from and at 212 

degrees, pounds 2,434 

Coal of usual mixture consumed, 

approximately, pounds 4,850 

Water per pound of coal — approx- 
imately, pounds 5 . 93 

Water per pound of coal from and at 

212 degrees (f = 1 . 1004) pounds. 6 . 52 

Average boiler horse power developed . . 70.6 

Rated horse power of boilers 414 

Per cent rated horse power devel- 
oped 17.2 

Owing to running the boilers at only 17.2 per cent 
of their normal rated capacity the consumption of 
fuel is way out of proportion to the production of 
steam. If a single boiler could carry the night load 
the combustion would be improved and less coal 
would be burned. 

To check up the results two tests on the flue gases 
were made which showed 3 per cent to 33^2 P er cen ^ 
of C0 2 . This simply means that several hundred 
per cent excess air is admitted to the fire owing to 
the large percentage of unused or dead grate surface. 

This test does not show what the maximum night 
heating requirements may be, as the outside tem- 
perature was only 43 degrees at midnight, and the 
large fan was run only 7^ hours out of the 13 hours 
of the test. The data and results of tests on No. 1 
boiler are given on pages 523 to 529. For con- 
venience of typographical arrangement the flue-gas 
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530 PREVENTING POWER-PLANT LOSSES 



BOILER-PLANT CAPACITY 

The normal rating of each of the horizontal tubular 
boilers is 207 boiler horse power. This rating pro- 
vides 12 square feet of water-heating surface per 
horse power. (Two boilers = 414 rated horse power.) 

A boiler horse power means the evaporation of 34}^ 
pounds of water into steam at atmospheric pressure 
from a feed-water temperature of 212 degrees F. 

With the prevailing conditions as to temperature 
of feed water and boiler pressure at this plant, the 
factor of evaporation is 1.097, so that it takes 31.5 
pounds of water actual weight at this feed tempera- 
ature to produce a boiler horse power. (That is, 
31.5 X 1.097 = 34.5.) 

It is good practice to force boilers of this type 50 
per cent above normal rating, so that (150 per 
cent X 414 horse power) = 622 boiler horse power 
may be had if required. 

The engine consumed 19.32 pounds of steam 
(water) per horse power per hour, whereas in this 
plant a boiler horse power is 31.5 pounds of water. 
Therefore under these conditions an engine horse 
power is 19.32 -5- 31.5 = 61.4 per cent of a boiler 
horse power. 

If therefore the engine were speeded up and were 
to operate at 300 horse power continuously, it 
would require only 61.4 per cent of 300 = 184.2 
boiler horse power. This would leave for process 
work, heating, or additional power 622 — 184 = 438 
boiler horse power. Now actual tests on steam 
required at this time (October and November) of 
year for heating and mill processes showed 70 boiler 
horse power at night and from 87.5 boiler horse 
power and 97.2 boiler horse power to 178.3 boiler 
horse power average loads, and for a single hour 
ran up to 229 boiler horse power. 

Suppose in the winter time the mill requirement 
should be just double the highest average obtained 



REPORTS 531 

in the highest test, i.e., 2 X 178 = 356.6 boiler 
horse power. Suppose at the same time the engine 
is taking its maximum of 184.2 boiler horse power, 
then the total extreme maximum requirements 
would be 184.2 + 356.6 = 540.8 boiler horse 
power. Even under these conditions there would 
still be 622 — 541 = 81 boiler horse power available 
for any purpose desired. 

BOILER-PLANT EFFICIENCY 

During the day run, when a greater proportion of 
coal is burned, this plant is operating at very high 
efficiency — considerably higher, in fact, than the 
average factory boiler-plant. This high efficiency 
may be attributed principally to the combination 
of small grate-surface and good grade of cheap an- 
thracite, mixed with enough slack to make it free- 
burning, and to good handling of the fire, together 
with the system of forced draft in use. 

Average boiler-plant efficiency will not as a rule 
run over from 61 to 64 or 65 per cent, and in many 
cases will be found as low as 55 per cent, and some- 
times as low as 50 per cent. 

Boiler efficiency simply means that percentage of 
the available heat in the coal which is converted into 
useful steam. At this plant this efficiency in a day 
run was determined under regular working condi- 
tions, and was found to be 7lVio per cent. This 
is unusually good when it is considered that the 
plant was operating at only a little over one-half 
its normal rated capacity. That is, in the two 
efficiency tests made one boiler developed 106.8 
horse power and 120.5 horse power as compared to 
its normal rating of 207 horse power. 

A rough test was made to determine the economy 
of the present system of blowers for producing forced 
draft. These tests would give only approximate 
results, but at the same time would be a close 



532 PREVENTING POWER-PLANT LOSSES 

enough check to show whether any great waste is 
going on at this point. The writer has made tests 
on three different steam-induced draft appliances, 
these tests all being made in the same manner, and 
the system found here has given apparently better 
results than either of the other two referred to. 

The amount of steam consumed in the blower when 
it is on- at its full capacity, that is, two nozzles of 
3 /i6 inch diameter, would be in the neighborhood 
of 6 boiler horse power per hour for each blower. 
This would be 12 horse power for two nozzles which 
constitute a blower for one boiler. Under these 
conditions a single boiler would be developing prob- 
ably in the neighborhood of 400 horse power, so 
that the percentage of steam used by the blower 
consisting of two nozzles would be 3 per cent of the 
boiler output. 

Additional tests were made during the efficiency 
tests. The steam from a nozzle connected up sim- 
ilarly to the nozzles of the draft appliance was in- 
serted in a barrel of water and the condensation was 
weighed. The end of the nozzle was inserted the 
same distance below the surface of the water as there 
were inches of draft pressure produced in the ash- 
pit. The result of this test gave approximately 0.4 
of a boiler horse power per hour, which divided by 
107.2, the horse power developed by the boiler, gives 
a consumption of 0.38 of 1 per cent as the amount 
of steam used by the boiler when the latter is run 
at about one-half its capacity. This percentage 
would increase when the draft is on a greater part 
of the time. 

The flue-gas analyses made during the efficiency 
test gave an excellent check on the results obtained. 
These gas analyses show a very high degree of com- 
bustion and an excellent regulation of the air 
supply under the light-load conditions. The amount 
of grate surface used at this plant is very small com- 
pared with what is usually found for burning poor 



REPORTS 533 

grades of anthracite. The usual ratio of water- 
heating surface to grate surface would be about 
40 to 1, whereas in this plant the ratio is 66.25 to 1. 
This is good practice as long as sufficient capacity 
can be obtained, but it is quite possible that under 
future conditions it will be necessary to enlarge this 
grate surface by increasing the length. This can be 
regulated according to requirements. (This change 
was made later on when more steam was needed.) 

An efficiency test was also made burning slack 
bituminous coal. The result was only 64.2 per cent 
efficiency as compared to 71.1 per cent with the 
anthracite coal. The cost of evaporation with the 
bituminous coal alone was $0.1473, as compared to 
$0.1133 for the dust. (The grates and furnace are 
not adapted to soft coal.) 

The actual calorific values of these two coals 
were: mixture five parts dust to one part slack, 
12,011 B.t.u. available heat, and for the slack as 
found in the test, 12,673 B.t.u. available heat. 
Now a ton of 2,000 pounds of the mixture costs $2.00 
at the fire-room, whereas the bituminous costs 
$2;48 for 2,000 pounds. If the bituminous coal were 
burned at an efficiency equal to that obtained in the 
mixture test, the cost of evaporation with the bitu- 
minous coal would still be 13.3 cents as compared 
to 11.3 cents for the mixture of dust as tested. 

In conclusion the writer would state that this 
plant has unusual value in the quality and price of 
coal as used. Also the thermal efficiency of the 
plant is high owing to the equipment and operation, 
as above described. Combination of these two fac- 
tors results in very low cost for evaporation. For 
purpose of comparison, a plant in Worcester which 
has improved combustion apparatus and is running 
at a higher thermal efficiency than this plant has 
to pay $3.75 for coal, and the consequent cost for 
evaporation runs about 15 cents per thousand 
pounds as compared to 11.3 cents at this plant. 



534 



PREVENTING POWER-PLANT LOSSES 



POWER-PLANT OPERATING COSTS 

(Not Including Purchased Power) 
For the Year 1908 



A — Total Light, Heat and 






Power Acct 


$2,237.17 




Including Labor (engineer, 


Aug. 1909 


day; fireman, day and 




$197.39 


night) 




Sept. 1909 


Labor of repairs 




$175.62 


Labor of maintenance 






Labor of maintenance of 






motors 






(24 days each month) 






B — Supplies 


$4,921.05 




Including oil, waste, fuel 


Aug. 1909 


($3,201, dust; $911, slack; 




$465.80 


$4,112, fuel total), repair 




Sept. 1909 


supplies, etc. 




$365.21 


(24 days each month) 







Days of actual opeiation in 1908, 263. 

Average day cost for 1908, actual operating days, 
$27.60. 

Total operating cost 1908, $7,158. 

The fuel therefore costs 4,112 -^ 7,158 = 57.3 
per cent of total operating costs. This includes 
heating. 

15 per cent depreciation and interest on $20,000 
plant = $3,000 year to add to the above costs. 

Including depreciation and interest, the fuel cost 
is 4,112 -f- 10,158 = 40.5 per cent of total cost of 
operating plant for heat and power. 



REPORTS 
COAL USED, AUGUST, 1909 



535 



Dust 



Slack 



August 1909. 
Sept. 1909 . . . 



120 tons— $229.56 
125 tons— $237.50 



24 tons— $57.70 

25 tons— $60.00 



PURCHASED CURRENT, YEAR 1908 

C— Light $209.74 

August 1909— $11.87 
Sept. 1909 — 16.01 

Power 3,819.84 

August 1909— $304.08 
Sept. 1909 — 275.80 

Average day cost purchased, based on actual days 
operation — 

Power $14.52 

Light 0.80 



COST OF POWER WITH PRESENT PLANT 

From a boiler test made for the purpose it was 
found that a 5 to 1 (by weight) mixture of anthracite 
dust and slack costing $2.00 a short ton at the fire- 
room, would give under working conditions an evap- 
oration of 8.06 pounds less 0.38 per cent used by 
blower = 8.03 pounds water evaporated per pound 
of coal under actual conditions. 

From an all-day engine test under actual working 
conditions it was found that 19.32 pounds of water 
(steam) was required per indicated horse power per 
hour. Therefore one indicated horse-power hour con- 
sumes 19.32 -=- 8.03 = 2.407 pounds of $2.00 coal. 
Hence the coal cost of producing one indicated horse- 



536 PREVENTING POWER-PLANT LOSSES 

power hour is (2.407 -h 2,000) X 2.00 = $0.002407. 
Adding 10 per cent to this figure for stand-by losses 
gives : 

I — Fuel cost per indicated horse power 
per hour $0.002648 

DEPRECIATION AND INTEREST CHARGES ON THE 
STEAM PLANT 

Appraising the plant, including boilers, settings, 
chimney, engine foundations, piping, and buildings, 
at their cost of $20,000 and charging 5 per cent (a 
generous allowance for depreciation and interest) 
gives a yearly charge of $3,000. 

Now from tests made for the purpose it was found 
that the heating of the mill and process work alone 
required : 

Heating and Mill-Process Work 

Day, 178 X 11 = 1,958 boiler horse-power hours 
Night, 70 X 13 = 910 " 



Total heating and 

process 2,868 boiler horse-power hours 

Engine Power 
172 i. h. p. X 11 

(hours) = . . . . 1,892 engine horse-power hours 
. (19.32 4- 31.5) X 

1,892 = 1,162 boiler horse-power hours 

2,868 heating alone 



Total boiler out- 
put = 4,030 boiler horse-power hours 

Hence the proportion of steam used for power is 
1,162 -r- 4,030 or 28.8 per cent of the steam produced 
in the boiler plant. Therefore only 28.8 per cent of 
boiler-plant charges should be made to the engine. 
The appraisal of the boiler plant, building and stack 



REPORTS 537 

is $13,000 and the engine plant and building $7,000. 
Therefore the depreciation and interest chargeable 
to power production alone is 28.8 per cent of 15 per 
cent of $13,000 plus 15 per cent on $7,000. 

15 per cent of $7,000 $1,050 

28.8 per cent of 15 per cent of $13,000. . . 562 



Total Depreciation and interest to power $1,612 

per year 
With 300 working days this would be 1,612 -r- 

300 = $5.38 a day 

In the all-day engine test the average indicated 
horse power developed for 11 hours was 172.8, so that 
172.8 X 11 = 1,901 indicated horse-power hours 
were produced. 

It is obvious that the depreciation and interest 
cost per horse power is inversely proportional to the 
number of horse-power hours produced, so that in 
taking 172.8 horse power, a low average, the resulting 
horse-power cost will be on the safe side, that is to 
say, sufficiently high. 

II — The Depreciation and Interest Charge is 
= $0.00283 per indicated horse-power hour. 

The Operating Charges are: 

Total operating charges based on actual days 
operation in year 1908 and also in August, 1909 (the 
September operating charges were less than August 
with the same number of operating days), = $27.60 

Now the cost of coal included in "Total Operating 
Charges" amounts to $4,112 -r- 7,158 or 57.3 per cent ■ 
of these charges. Hence daily operating charges less 
fuel are: 

100 per cent — 57.3 per cent = 42.7 per 
cent of $27.60 $11.78 



538 PREVENTING POWER-PLANT LOSSES 

By analyzing this charge, it is evident that not 
over half is chargeable to the engine plant. 

$11.78 -s- 2 = $5.89 = daily operating charge 
to engine power and $5.89 -v- 1901 = 

III — Operating Cost per Indicated Horse-power 
Hour = $0.003098 

Charges per Indicated Horse-Power Hour 

I— Fuel cost. $0.002648 

II — Depreciation and interest 0.002830 

III— Operating (less fuel) 0.003098 

IV — Total Cost per Indicated Horse- 
power Hour $0.008576 

Now a kilowatt without consideration of losses is 
equal to V/i horse power. But in converting from 
indicated horse power to current at the generator 
terminals, an allowance for engine friction and 
dynamo loss makes it necessary to multiply the indi- 
cated horse-power cost by 1.54 to get the cost of 
an effective kilowatt hour. 

V— Cost of Effective Kilowatt Hour (1.54 X 
$0.008576) = $0.0132 

COST PER KILOWATT HOUR IF 300 INDICATED HORSE 

POWER WERE DEVELOPED CONTINUOUSLY ON THE 

DAY RUN INSTEAD OF 172 INDICATED HORSE 

POWER AS FOUND 

300 indicated horse power X 11 (hours) = 3,300 
indicated horse-power hours. 

Coal per indicated horse power would remain sub- 
stantially the same if the engine is speeded up 10 per 
cent and run at 21 per cent overload to produce 300 
horse power. Under these conditions and if the 
engine is overhauled and tuned up, the same steam 
consumption per horse power is a fair assumption. 
Hence : 



539 



I — Fuel Cost per Indicated Horse Power per Hour 
= $0.002648 

Depreciation and Interest. The conditions now 
would be: 

The- boiler plant produces 

For heating and 

mill work 2,868 boiler horse-power hours 

For the engine 11 

X 300 X (19.32 

-^ 31.5) 2,024 " " u 

Total boiler horse- 
power hours. . .4,892 

Engine consumes 2,024 + 4,892 = 41.4 per cent of 

the total boiler output. 
Hence depreciation and interest chargeable to engine 

is: 

15 per cent of $7,000 a year $1,050 

41.4 per cent of 15 per cent of $13,000 a 
year 807 

Total yearly $1,857 

This is 1,857 -v- 300 = $6.19 a day, and divided by 
3,300 horse-power hours gives: 

n — Depreciation and Interest per Indicated Horse- 
power Hour = $0.001876 

The daily operating charge of $5.89 to engine is 
the same as when only 172 horse power was developed. 
Hence for 300 indicated horse power or 3,300 indi- 
cated horse-power hours 

III — Operating Charge per Indicated Horse-power 
Hour is $5.89 -T- 3,300 = $0.001785 
Summing up items I, II and III, the total cost of 
producing an indicated horse-power hour would be: 



540 PREVENTING POWER-PLANT LOSSES 

I — Fuel per indicated horse-power 

hour $0.002648 

II — Depreciation and interest per 

indicated horse-power hour. . 0.001876 
III — Operating cost per indicated 

horse-power hour 0.001785 

Total cost per indicated horse- 
power hour $0.006309 

The cost per effective kilowatt hour is then (multiply 
by 1.5 '4) $0.00971 or less than one cent per kilowatt 
hour. 

It is therefore determined that under actual con- 
ditions this plant is making its own power, including 
all charges, for $0.0132 per kilowatt hour as com- 
pared with $0,020 to $0,025 per kilowatt hour for 
purchased electric power. 

If the present plant is speeded up 10 per cent and 
operated at an average of 300 horse power on the day 
run of 11 hours, a kilowatt hour can be produced for less 
than one cent as above determined. 

The conclusion is that it would be a losing propo- 
sition to discontinue the presenjt engine plant. 

ENGINE TEST 

An all-day test was made on the main engine to 
determine the indicated horse power every 15 min- 
utes and to find the steam and fuel consumption and 
therefore the fuel cost per horse power per hour under 
actual operating conditions. 

For this purpose, boiler No. 1 was connected and 
blanked off exclusively to the engine with its con- 
denser and reheater. 

Date Oct. 25, 1909 

Duration 7.30 a. m. to 6.00 p. m. -. . . 10.5 hours 
Engine running . 10.417 hours 



REPORTS 541 

Steam pressure 118 lb. 

Vacuum of condenser 26 inches 

Temperature of feed water 161 degrees 

Temperature of injection water 54 degrees 

Temperature of water leaving con- 
denser 84 < ~ 

Maximum indicated horse power 218 

Minimum indicated horse power (at 

noon hour) 95 

Average indicated horse power 172.8 

Rated h. p. of engine at 86 r. p. m.. . 225 

Average indicated horse power divi- 
ded by rated h. p 76.8 per cent 

Steam used per indicated horse power 
per hour under factory conditions, 
including steam to condenser and 

receiver 19.32 lb. 

Total steam used in 10.5 hours 34,795 lb. 

Total steam used per hour (10.417). . 3,340 lb. 

(For cost per indicated horse-power 
hour see " Cost of producing power 
with present equipment.") 

CAPACITY 

In later tests a card showing 265 indicated horse 
power was taken from the engine. This was at the 
heaviest part of the day load, when the lighting 
generator was on. This was the heaviest load 
obtained, although the indicators were kept on the 
engine for more than a week. It seems quite possible, 
however, that the engine may at times carry loads up 
to 300 horse power as claimed by the engineer, espe- 
cially when the mill is working up to the full capacity 
on heavy grades of stock. 

This engine may therefore be considered as doing 
its full duty as regards load. 



542 PREVENTING POWER-PLANT LOSSES 



Electric Power. Cost of Making versus Buying 

To take care of full motor load now purchased — 
day 91 horse power, 68 kilowatts, night 109 horse 
power, 81.7 kilowatts. It would be well to put in 
a 90-kilowatt generator set. It would operate at 
times, for short periods, at as low as 10 -s- 90 = one- 
ninth capacity but on the average at about 27 -f- 
90 = about one-third normal rating. If all the 
motors which run at one time should happen to 
carry their full rated load, then the 90-kilowatt 
generator set would also work at nearly normal full 
load, and would in addition provide for temporary 
overloads as high as 25 per cent, i. e., up to 112.5 
kilowatts. 

The best economy with such an arrangement for 
displacing the present purchased electric power 
would be to run this unit non-condensing and utilize 
the exhaust steam from same in the present heating- 
fan coils, in the proposed new fan coils, in a feed- 
water heater, and also for heating the office. In 
warm weather when the exhaust-steam heating 
became less than 25 per cent of the steam produced 
by the engine, the engine should be run condensing. 

For purposes of comparison with purchased elec- 
tric power the most disadvantageous conditions will 
be assumed, i. e., the exhaust not utilized at all and 
engine run non-condensing. Further, the engine 
will be assumed to be a simple Corliss of 125 revo- 
lutions. 

The average water consumption would be high 
under these variable conditions of load and will be 
put at 30 pounds per indicated horse-power hour. 

Under these conditions the fuel cost per indicated 
horse power per hour would be 30 -v- 8.03 = 3.736 
pounds of $2.00 coal. That is (3.736 -f- 2,000) X 
$2.00 = $0.003736 per horse power per hour; or this 
equals $0.00635 for coal per kilowatt hour (at 1.7 
indicated horse power = 1 kilowatt at switchboard). 



REPORTS 543 

I— Fuel Cost per Kilowatt Hour (1.7 X $0.003736) 
non-condensing and with no exhaust utilized = 
$0.00635. 

The depreciation and interest chargeable against 
this new unit would be only the charges against the 
new investment. To be on the safe side call the 
investment $8,000 to cover changes in engine room, 
foundations, piping, engine, generator, exciter, 
switchboard, wiring and all possible expenses. 
$8,000 X 15 per cent = $1,200 per year 4- 300 = 
$4.00 per day. 

Dividing this by the present small load of 582 
kilowatt hours per day of 24 hours we shall have as 

II — Maximum Depreciation and Interest with 
present load based on an investment of $8,000, 

($4.00 -v- 582) = $0.00688. 

Maximum Depreciation and Interest based on 
probable future load of 1,000 kilowatt hours, 
($4.00 -r- 1,000) = $0.00400. 

Now the operating cost outside of fuel stated in 
(I) would not be increased except for oil and waste 
and half the time of a night man who would attend 
to the boilers as well. The oil and waste would be 
more than balanced by the saving in coal by the 
employment of the night man. Hence the added 
operating cost properly changeable against the new 
unit will be : — 

IH — Operating Cost per Kilowatt Hour 

based on present load (1.165 -r- 

582) $0.00201 

Operating Cost per Kilowatt Hour 
based on probable future load of 
1,000 kilowatt hours per 24 hours 
(1.165^ 1,000) $0.001165 



544 PREVENTING POWER-PLANT LOSSES 



Summary of Costs for Proposed New Unit Per 
Kilowatt Hour with Present Electric Load 

I — Fuel, with x /i exhaust utilized the 
year round, a safe estimate based on tests 
and data of the investigation — 55 per cent 
of total steam chargeable to engines 
(0.55 X $0.00635) $0.00349 

II — Interest, Depreciation, etc., based on 
present load of 582 kilowatt hours per 24 
hours 0.00688 

III — Operating Charges based on present ' 
load— 582 kilowatt hours . 00201 

Total per kilowatt hour $0 . 01238 

Per Kilowatt Hour with Probable Future Load 

I — Fuel with Y^ exhaust utilized, 55 per 
cent of steam chargeable against engine 
(0.55 X $0.00625) $0.00349 

II — Interest, Depreciation, etc., based on 
1,000 kilowatt hours per 24 hours . 00400 

III — Operating Charges based on 1,000 
kilowatt hours 0.00116 

Total per kilowatt hour $0 . 00865 

These figures do not include the use of a condenser 
in the warm months. 

Furthermore, as the plant grows the kilowatt- 
hour cost will decrease below the "above figures, and 
the constantly increasing use for exhaust steam will 
still further reduce the cost of power from this unit. 

Electric Power Required 

From the bill for electric power for the year 1908, 
$3,819.84 -=- 263 working days = $14.52 a day. 
At 2J^ cents per kilowatt hour, the amount of 



REPORTS 545 

power purchased must have been 1,452 -f- 2.5 = 
582 kilowatt hours a day on the average. Based 
on a 20-hour working day for the motors, this would 
mean an average continuous power of 582 -f- 20 = 
29.1 kilowatts. 
An all-night test of the electric load 

gave an average load of 21.5 kilowatts 

A minimum load of 10 

A maximum load of 31.3 

Test made in the day time (nine hours) showed the 
load to vary from 1.64 at noon and 9 kilowatts at 
other times to 37 kilowatts. The average for eight 
hours (excepting noon) was 32.5 kilowatts. Still 
another test showed as high as 52 . 5 kilowatts in the 
day time. 

Figuring on the rating of the motors would give 
possible normal motor loads as follows : 

Horse Horse 

Day Time Power Night Time Power 

Machine shop motor 7 Fulling-room motor . 75 

Scouring motor .... 35 Heating-fan motor. . 30 

Heating fan 30 Power-pump motor . 4 

Power-pump fan ... 4 
Spinning-room fan. . 15 

91 109 

(or 68.3 kilowatts) (or 81.7 kilowatts) 

The average electric-motor load may be considered 
at present as about 30.2 kilowatts. 
Day-time test (9 hours) large heating 

fan not on, average load was 30.2 kilowatts 

The possible maximum according to 

rating of motors on in day time .... 68.3 " 
Large fan motor in test consumed 

about 13 " 

(The belt was slipping so this power 

is below. normal) 



546 PREVENTING POWER-PLANT LOSSES 

Night average electric load. 21.5 kilowatts 

The possible maximum according to 
rating of motors on at night 81.7 

Note : t The f ulling-room is run by engine in day 
time and attached to 75 horse-power motor at night. 



REPORT ON OPERATION AFTER INSTALLATION 
OF RECOMMENDATIONS 



INDEX TO REPORT Pap-P 

Object of the Investigation 546 

Condensed Results of the Investigation 547 

Plan of Tests 550 

' New Engine — Steam Pressure 551 

Effect of Speeding up Main Engine 551 

Test No. 1 Main Engine and Generator 552 

Test No. 2 New Engine and Generator 554 

Cost Data from the Books 558 

Notes on Charges against Engine 559 

OBJECT OF TESTS 

The object of the following tests was to deter- 
mine the present cost of generating power under 
the new conditions; and further to compare the 
present costs with those obtained when the plant 
was tested in October and November, 1910, following 
which test recommendations were made covering 
certain changes which are now in operation. 

The principal changes that were recommended 
and adopted were as follows: — 

1 — Install a 120 horse-power simple Corliss engine 
with generator to displace about 30 kilowatts of 
purchased electric power and to provide 60 kilo- 
watts for taking care of increases in machine load 
as added from time to time. 



REPORTS 547 

2 — Install a first-class vacuum system and utilize 
the exhaust steam to heat the mill instead of 
live steam then in use. 

3 — Speed up the main engine in order to increase its 
capacity. 

CONDENSED RESULTS OF THE INVESTIGATION 

Present Cost of Power. — Under present condi- 
tions the total cost of making power, including all 
charges, with the main engine is $0.01043 per kilo- 
watt hour delivered on the bus bars. 

The result of installing the new Corliss engine with 
a 90-kilowatt generator has been to displace electric 
power formerly purchased at the rate of $0,025 per 
kilowatt hour and to make this power a tthe rate 
of $0.00937 per kilowatt hour when the output is 
1,000 kilowatt hours per day, the present low aver- 
age. 

From tests that have been made it was found that 
over one-half the exhaust steam produced by this 
new unit is utilized in place of live steam formerly 
used, based on a year-round consumption. But in 
the above cost deduction only one-half the heat in 
the exhaust has been credited to the engine. 

It is of special note that the above cost is being 
produced under disadvantageous conditions. That 
is to say, the new engine was ^designed to run on 120 
pounds boiler pressure. As a matter of fact, the 
test" was made with only 74 pounds steam pressure 
at the engine. It is my opinion that a reduction in 
steam consumption of the engine of 10 per cent 
would be made by operating with 120 pounds steam 
pressure instead of 74 pounds as at present, now 
that the load has sufficiently increased to prevent 
valve and regulation difficulties. 

It will be further noted that the above costs per 
kilowatt closely agree with those predicted in the 
writer's report made in the fall of 1909. 



548 PREVENTING POWER-PLANT LOSSES 

The X heating system with Y valves has given 
satisfaction according to report of th.e superintendent 
and engineer, and has resulted in the advantage of 
being able to heat the buildings with exhaust steam 
where live steam was formerly and exclusively used. 
It has also been possible by means of the vacuum 
system to apply exhaust steam to other purposes 
where live steam was formerly employed. With the 
use of the X system no back pressure is required in 
order to provide circulation of steam in the heating 
system. 

Both power and heating requirements have been 
largely increased since the writer's visit in 1910. 
The power comparison may be stated as follows on a 
basis of 24-hours output: 

Kilowatt Hours 

Main engine, 1910 1,150 

Main engine, 1912 1,600 

Increase of power on main engine 450 or 39 

per cent 
Old Albany Southern power 1910 666 
New engine power displacing 

above, 1912 1,070 

Increase 404 or 61 

per cent 
Increase of power based on totals: 

Former power 1,816 

Present power 2,670 

Increased power 854 or 47 

per cent 

As a practical check on the above results the 
following figures from the Company's books may 
be quoted: With the 47 per cent increase of power 
as above shown, the heating requirements of the 
mill have also been increased at least 50 per cent 
owing to the large additions that have been made, 
which additions are very largely exposed to the 



REPORTS 549 

weather and contain a very great percentage of 
window space. 

Day Cost. — As a check on statements otherwise 
derived the following may be quoted : The total day 
operating cost of power, heat and light for 1910 
was $25.40. For the seven months' operation of 
the new system with about 50 per cent increase of 
power, heat and light, the day cost was $30.60, 
showing an increase of $5.20 a day, which is equal 
to 20.5 per cent increase of operating cost. 

Savings. — The work of the new engine and gen- 
erator from a recent reading is 1,070 kilowatt hours 
per day, and this load is continually increasing. At 
the old rate of 23^ cents this would cost $26.75 per 
day. 

The present cost with new engine for the same 
power as above is 1,070 X $0.00937 = $70 per day, 
thus making a saving of $16.75 per day or $5,025 
per year. This is a conservative figure, since the 
power requirements are increasing steadily* with the 
installation of new machinery, and the use of ex- 
haust steam is also growing. 

If you had accepted the offer of the electric power 
company to supply all your power at the rate of 2 
cents per kilowatt hour instead of adopting the plan 
recommended in the first report, your total power 
expense would be $8,010 a year more than it is at 
present. That is to say, you would be paying for 
2,670 kilowatt hours per day at a 2-cent instead of a 
1-cent rate. 

A larger operating charge than is truly propor- 
tional has been made against the new engine in 
order to be on the safe side in the estimates of 
savings accomplished. Otherwise the predicted and 
actual costs for power under the new system will 
be seen to agree closely by comparing the original 
report with the present one. 

The saving due to speeding up the main engine 



550 PREVENTING POWER-PLANT LOSSES 

may be considered as equal to the extra power so 
provided compared to purchasing this power. On 
the basis of a safe estimate, as elsewhere calculated 
in this report, this saving amounts to at least $450 
per year. 

The total savings from these two changes are 
therefore $5,025 + $450 = $5,475 per year. If $150 
per year be deducted as interest charges on changes 
to heating system, the net saving is $5,325 per 
annum. The net interest or dividend on investment 
is 5,325 -r- (7,000 + 1,000) = 66.5 per cent. 

PLAN OF TESTS 

Test No. 1. — The fuel cost of the main engine 
per horse power and per kilowatt hour was obtained 
in a 43/2-hour run by measuring the water fed to the 
single boiler which was connected to supply steam 
to this engine alone. The water was measured in 
barrels calibrated by weighing. Indicator cards 
were taken periodically throughout the test together 
with switchboard readings showing electrical output 
at the bus bars. 

Test No. 2. — The fuel costs of the new simple 
non-condensing engine were obtained in a separate 
test of three hours' duration in the same way as in 
Test No. 1. 

Test No. 3. — The total steam produced by both 
boilers under present conditions was obtained by 
making a capacity test on the two boilers at the same 
time, all water fed being measured -in the calibrated 
barrels and all necessary readings being taken. 

During this test a record was kept of the electrical 
output of each engine, from which figures, and from 
the steam per kilowatt hour determined in Tests 
Nos. 1 and 2, it was possible to learn what proportion 
of the total steam generated in the boilers is con- 
sumed by the engines and by the mill respectively 
under working conditions in cold weather. 



REPORTS 551 

Electrical Testing. — In addition to the above 
work the electrical installation was inspected and the 
meters were tested for accuracy. Following this, a 
report was made on electrical conditions as found, 
together with certain recommendations for im- 
provement. 

NEW ENGINE STEAM PRESSURE 

Owing to the light fractional load at one time 
carried by the new engine it was necessary to install 
a pressure-reducing valve. The day load has now 
increased to a point where this reduced pressure (75 
pounds) is unnecessary and furthermore is wasteful 
of steam. 

I would therefore recommend by-passing enough 
steam from the mill line, by means of the present 
by-pass, to build up the pressure in the engine line 
to 115 pounds. This will increase the horse power 
of the engine more than 50 per cent, give it a much 
earlier cut-off, and make a material reduction in 
the consumption of steam. 

At night or at times when there may be too light 
a load, the by-pass valve can be closed and the 
engine operated through the reducing valve. 

EFFECT OF SPEEDING UP MAIN ENGINE 

The effect of speeding up the main engine may be 
stated in terms of dollars as follows : 

Present output of main en- 
gine, per day 1,600 kilowatt hours 

Former output 173 horse 

power equal to, per day. . 1,150 kilowatt hours 

Per cent increase in load ... 39 per cent 

Although a part of this 39 per cent could have been 
added to the former load, it would not have been good 
or economical practice to have added more than 30 



552 PREVENTING POWER-PLANT LOSSES 

per cent at the former speed. Hence, a mimimum 
estimate of the power gained by speeding up may be 
considered as equal to about 10 kilowatt or 100 kilo- 
watt hours per day which would have otherwise to be 
purchased at V/i cents or made by the new engine. 
But considering this as a separate proposition, the 
saving can be safely estimated at 1.5 cents per kilo- 
watt hour, or $1.50 per day, or $450 per year. 

Test No. 1. Main Engine and Generator 

Engine: Knowlson & Kelly 14 %, X 26^ X 36, 
97 to 100 r. p. m., cross-compound condensing, belt- 
connected to a 180-kilowatt alternating-current gen- 
erator, 240-volt, 3-phase, 25-cycle 

Date of test Jan. 20, 1912 

Duration of test 4J/2 hours 

Boiler pressure by gage, average .... 109.4 lb. 

Vacuum by gage, average , 25.7 inches 

Receiver pressure (variable) 9 to 20 lb. 

Temperature of feed water (for test 

only) 89 degrees 

Maximum kilowatt reading on bus 

bars 180 

Minimum kilowatt reading on bus 

bars 125 

Average kilowatts per hour 155 

Average indicated horse power per 

hour 232.5 

Actual weight of steam per kilowatt 

hour. . 29.14 1b. 

Actual weight of steam per indicated 

horse-power hour 19.43 lb. 

Indicated horse power per kilowatt on 

bus bars 1.5 

Rated capacity of engine at 100 

r. p. m 300 

Percentage of rated capacity devel- 
oped (232.5 + 300) 77.5 per cent 



REPORTS 553 

Coal per kilowatt hour on bus bars. . 3.63 ib. 
Coal per indicated horse power per 

hour 2.42 lb. 

F.uel cost per kilowatt hour $0.00363 

Fuel cost per indicated horse-power 

hour $0.00242 

Note : The fuel cost of making steam in the boilers 
is taken from tests made in October and November, 
1910. This is done as no change which would affect 
this cost has been made in the boiler plant. 

DEPRECIATION AND INTEREST CHARGES 

No increase of these charges has occurred since 
Report of 1910, and referring to that report, it will 
be seen that the total amount was $3,000 per year on 
the whole steam plant. 

Now from data obtained it is determined that 
70 per cent of the maximum boiler output is re- 
quired for purposes other than the main engine. 
(See former report.) A greater proportion of steam 
is now used for heating. 

Depreciation and interest of boiler plant 
chargeable to main engine per year is 30 
per cent X (15 per cent X 13,000) = . . $585.00 

Depreciation and interest on engine plant, 

15 per cent X 7,000 1,050.00 

Total depreciation and interest charged to 

main engine per year $1,635.00 

Total depreciation and interest charged to 

main engine per day $5.46 

Taking the average output of the main en- 
gine set at 1,600 kilowatt hours we have: 

Depreciation and interest charge per kilo- 
watt hour on main engine set ($5.46 -f- 
1,600) $0.00341 



554 PREVENTING POWER-PLANT LOSSES 



OPERATING CHARGES 

Total operating charges based on actual 
days operation from June 1 to Dec. 31, 
1911, i. e., 7 months of average tempera- 
ture, during which time the new power 
system was in operation (fuel expense 

deducted) per day $12.02 

By analyzing this item, it is found that 
Expense chargeable to engine room (both 

engines), is, per day 8.00 

Operating charge to new engine per day. . . 2.58 
Operating charge to main engine per day . . 5.42 
Operating charge to main engine per kilo- 
watt hour, 5.42 -f- 1,600 $0.00339 

Collecting the three cost items before deter- 
mined, we have : 

PER KILOWATT HOUR 

1— Fuel cost per kilowatt hour $0.00363 

2 — Depreciation and interest charges . . 0.00341 
3 — Operating charge except fuel ...... 0.00339 

Total cost per kilowatt hour $0.01043 

Total cost per indicated horse-power 

hour $0.00696 

Test No. 2. New Engine and Generator 

Engine: Knowlson & Kelly 14 X 30, 126 r. p. m. 
(during test); simple Corliss, non-condensing, belt- 
connected to a 90-kilowatt alternating-current gen- 
erator, 240-volt, 3-phase, 60-cycle 

Date of test Jan. 20, 1912 

Duration of test 3 hours 

Steam pressure low side of reducing 

valve 74 lb. 

Temperature of feed water (for test 

only) 53 degrees 



REPORTS 555 

Maximum kilowatt reading on bus 
bars 64.4 

Minimum kilowatt reading on bus 
bars 46.0 

Average kilowatts per hour 60.3 

Indicated horse power per kilowatt. . 1.6 

Average indicated horse power per 

hour 96.6 

Actual weight of steam per kilowatt 

hour 48.1 lb. 

Actual weight of steam per horse- 
power hour 30.0 lb. 

Rated capacity x of engine at 75 lb. 
initial pressure and 126 r. p. m. 
at 25 per cent cut-off 100 horse-power 

Percentage of this rated capacity 

developed 96.6 per cent 

Coal per kilowatt hour 5.98 lb. 

Coal per indicated horse-power hour 3.74 lb. 

Fuel cost per kilowatt hour $0.00598 

Fuel cost per indicated horse-power 

hour 10.00374 

Note: The cost of making 1,000 pounds of steair 
is taken from boiler tests made in October and No- 
vember, 1910. 

DEPRECIATION AND INTEREST CHARGES 

There is no charge to these accounts from the boiler 
house against this new engine; but the cost of the 
new engine, generator, foundations and its part of 
the switchboard and wiring are direct charges 
against the power developed. 

The cost of these items is taken from data on the 
books of the mill and amounts to less than $7,000. 
This cost is made up as follows : 

x At 1151b. initial pressure the rating of this engine would be 170 
horse power. 



556 PREVENTING POWER-PLANT LOSSES 

Engine $1,750 

Generators 1 ,700 

Foundations 500 

Piping . 300 

Wiring and construction 2,000 

Regulators 205 

Generator switchboard 400 

Total cost of new engine and generator $6,855 
Call this for safety .$7,000 

Depreciation and interest charges per 
year,_15 per cent of $7,000 . 1,050.00 

Depreciation and interest charges per 

day. . 3.50 

Depreciation and interest charges per 
kilowatt hour— ($3.50 -f- 1,000 kilo- 
watt hours per day) 0.0035 

Other charges against this generating set are: 

Cost per day for additional wages (from 
the books) 1.58 

Oil, waste and supplies (a very high figure 

from the books, which can be reduced) ... 1.00 

Total other charges per day 2.58 

Total other charges per kilowatt hour 

($2.58 + 1,000 kilowatt hours 1 ) 0.00258 

COST PER KILOWATT HOUR 

Summing up the Above Cost Items 

Depreciation and interest charges $0.00350 

"Other charges" 0.00258 

Fuel cost 0.00598 

Total cost per kilowatt hour $0.01206 

Total cost - per equivalent indicated 

horse-power hour $0.00754 

1 This total of 1,000 kilowatt hours per day was obtained from monthly- 
readings of the individual integrating watt-meter attached to generator 
of this engine. 



REPORTS 557 

In computing the above power cost no credit has 
been allowed for the utilization of exhaust steam. 
When all the exhaust is utilized, as in cold weather, 
it takes the place of 90 per cent of its weight of live 
steam. If one-half of the exhaust produced by this 
engine is utilized on an average the year round (a safe 
estimate) the fuel cost of steam chargeable to power 
will be reduced 45 per cent and the total cost per 
kilowatt hour will be as follows : 

Cost Per Kilowatt Hour 

Depreciation and interest $0.00350 

"Other charges" 0.00258 

Fuel cost 0.00329 

Total cost per kilowatt hour $0.00937 

If it be assumed that all the exhaust of this engine 
is wasted all the year round, the following compari- 
sons can be obtained : 





Exhaust of 
New Engine 
all Wasted 


One-half 
Exhaust 
Utilized 


1,000 kilowatt hours per 
day, present work of 
new engine 


$12.06 

25.00 
12.94 
3,882.00 
55.4 per cent 


$9 37 


1,000 kilowatt hours at 
2}/2 cents with pur- 
chased power 

Saving per day by new 
engine 


25.00 
15.63 


Saving per year by new 
engine — 300 days .... 

Interest (profits) on in- 
vestment 


4,689.00 
67.1 per cent 



558 PREVENTING POWER-PLANT LOSSES 

COST DATA FROM THE BOOKS 

Average cost per day for Power, Heat and Light. — 
These figures include everything but interest 
charges. 



Aug. 



Sept. 



Oct, 



Nov. 



Old system, pur- 
chasing power . . 

New system, mak- 
ing own power . . 



$35.25 
$28.96 



$37.13 

$26.57 



$31.89 
$29.40 



$37.36, 1910 
$33.51, 1911 



Average day cost 1908— $27.60— operating days 263 

" " 1909— 25.40— " " 284 

" " 1910— 31.65— " " 303 

" " 1911— 30.60— " " 178 

(May 31-Dec. 31) 

The new system was started in May, 1911, so that 
up to time of second investigation it has been run- 
ning about eight months. The average day cost 
for 1911 is taken from May 31 to Dec. 31, giving 
seven full months of about average temperature. 
About $1.00 per day should be added to these 
figures, which is paid to maintain the contract 
with the power company. 

The average daily power output for 1911 as com- 
pared with Oct. 25, 1909, is given opposite. 

"Day cost" does not include interest charges, but 
covers power, heat and light. 

The table on page 559 gives a rough comparison 
showing that while the day cost increased 20 per 
cent, the power used increased 333/2 per cent. These 
figures are favorable, especially in view of the large 
additions to the mill which have greatly increased 
the heating requirements. 



559 



Power developed or used 
per day, 24 hours 


Horse-power 
hours, 1909 


Horse-power 
hours, 1911 


Main engine 173 x 11 . . 

Purchased power 551 
kilowatt hours or new 
engine and generator . 


1,903 
735 


2,190 
1,332 


Total per day 

Average day cost 


2,638 
$25.40 


3,522 
$30.60 



Notes on Charges Against Engines 

The following principles were employed in com- 
puting the cost per kilowatt hour on the two gen- 
erating sets. 

The analysis of these percentage charges is as 
follows : 

A. Only about 30 per cent of the maximum ca- 
pacity of the boilers is required for the main en- 
gine, and while the remaining 70 per cent is not in 
use for mill and heating purposes continuously, yet 
this part has to be held in reserve strictly for these 
purposes. Therefore about 30 per cent of the fixed 
charges on the boiler plant is chargeable to the main 
engine and to the power it produces. 

As the exhaust steam from the new engine is 
utilized for heating, thus displacing the use of an 
equivalent amount of live steam, no additional 
boiler capacity was required on its account and 
therefore no fixed boiler-plant charges can be made 
against it. 

B. In the case of either engine, it is evident 
that their necessary fixed charges are to be charged 
against their respective power outputs. 



560 PREVENTING POWER-PLANT LOSSES 

In this connection it will be understood that the 
electrification of the mill and of the main engine 
constitute charges against the mill, and not against 
the cost of producing power. This is evident, for 
electric transmission was decided upon because of 
its benefits throughout the mill in various ways, 
but not at all for the purpose of producing power 
or for reducing its cost. It must properly be con- 
sidered as a system of transmitting the energy that 
was already being produced in a more convenient 
manner, the mill and not the engine room being 
considered. 

In the case of the new engine, on the other hand, 
the fixed charges resulting from the installation of 
its generator and switchboard must be included in 
the determination of the cost of power developed 
by this engine. This is evident for the reason that 
no other kind of an installation would have per- 
formed the function required; that is, of replacing 
the purchased electric power. This was the purpose 
of the new engine, and a generator and its fixings 
formed part of the necessary equipment. 

C. No operating charges on the boiler plant 
except fuel are charged against the new engine, 
since these costs are in no way changed, and since 
the combined night engineer and fireman is charged 
half-and-half to the engine and boilers. 

The additional wages of the day engineer are 
charged against the new engine, and one-half of the 
wages of the night engineer and fireman. 






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